Refrigerating apparatus

ABSTRACT

A refrigerating apparatus includes first and second refrigerant circuits including respective first and second compressors, condensers, pressure reducers, and evaporators, connected circularly with first and second refrigerant pipes, respectively, refrigerants discharged from the first and second compressors being respectively condensed at the first and second condensers and thereafter respectively evaporated at the first and second evaporators to acquire a cooling effect; a temperature sensor that detects a temperature of an internal portion of a cold storage cabinet, the first and second evaporators being disposed to cool the internal portion simultaneously; and a first control device that controls the first and second compressors such that both of them are operated each time a temperature detected by the temperature sensor reaches a first temperature, and the first and second compressors are alternately operated each time a temperature detected by the temperature sensor reaches a second temperature lower than the first temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of International Patent ApplicationNo. PCT/JP2009/66275 filed Sep. 17, 2009, which claims the benefit ofpriority to Japanese Patent Application No. 2008-243064 filed Sep. 22,2008. The full contents of the International Patent Application areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a refrigerating apparatus.

2. Description of the Related Art

A refrigerating apparatus is known that includes two refrigerantcircuits having compressors, condensers, pressure reducers, andevaporators (see, e.g., Japanese Patent Application Laid-OpenPublication No. 2005-90917). Since the refrigerant discharged from thecompressor in each of the two refrigerant circuits is cooled andliquefied by the condenser and evaporated by the evaporator after thedepressurization by the pressure reducer, for example, an internalportion of a cold storage cabinet in thermal contact with the twoevaporators in common is cooled.

This refrigerating apparatus includes a temperature sensor that detectsa temperature of the internal portion, and controls the respectivecompressors of the two refrigerant circuits in the following manner, forexample. That is, when one or both of the compressors of the tworefrigerant circuits are operated, a temperature detected by thetemperature sensor drops from an upper limit to a lower limit of apreset temperature range, and when both of the compressors of the tworefrigerant circuits are stopped, a temperature detected by thetemperature sensor increases from the lower limit to the upper limit ofthe preset temperature range. As above, the temperature of the internalportion is maintained within the preset temperature range by alternatelyperforming an operation of one or two of the compressors and a stoppingof the two compressors.

To accurately control the temperature in the internal portion (i.e., tomaintain within a predetermined set temperature range) in therefrigerating apparatus even in a case where an internal load has beenincreased due to an increase in an ambient temperature, etc., it isnecessary to relatively increase frequency (number of times per unittime) of periods during which both of the two compressors are inoperation by, for example, operating both of the two compressors duringthe period of operating the compressors and shortening the period inwhich both of the compressors are stopped.

However, in this case, since the number of activations of thecompressors is increased there are drawbacks including not only theshortening of lives of electric components such as relays but also anincrease in power consumption due to activation current.

It is therefore the object of the present invention to accuratelycontrol the internal temperature while suppressing the number ofactivations of the compressors.

SUMMARY OF THE INVENTION

A refrigerating apparatus according to an aspect of the presentinvention, comprises: a first refrigerant circuit including a firstcompressor, a first condenser, a first pressure reducer, and a firstevaporator, connected circularly with a first refrigerant pipe, arefrigerant discharged from the first compressor being condensed at thefirst condenser and thereafter evaporated at the first evaporator toacquire a cooling effect; a second refrigerant circuit including asecond compressor, a second condenser, a second pressure reducer, and asecond evaporator, connected circularly with a second refrigerant pipe,a refrigerant discharged from the second compressor being condensed atthe second condenser and thereafter evaporated at the second evaporatorto acquire a cooling effect; a temperature sensor configured to detect atemperature of an internal portion of a cold storage cabinet, the firstevaporator and the second evaporator being disposed to cool the internalportion at the same time; and a first control device configured tocontrol the first compressor and the second compressor in such a mannerthat both the first compressor and the second compressor are operatedeach time a temperature detected by the temperature sensor reaches afirst temperature, and the first compressor and the second compressorare alternately operated each time a temperature detected by thetemperature sensor reaches a second temperature lower than the firsttemperature.

Other features of the present invention will become apparent fromdescriptions of this specification and of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For more thorough understanding of the present invention and advantagesthereof, the following description should be read in conjunction withthe accompanying drawings, in which:

FIG. 1 is a front view of an example of a refrigerating apparatusaccording to a first embodiment;

FIG. 2 is a side view of the refrigerating apparatus of FIG. 1;

FIG. 3 is a circuit diagram of an example of a first refrigerant circuitand a second refrigerant circuit of the first embodiment;

FIG. 4 is a block diagram of an example of a control circuit responsiblefor controlling the first refrigerant circuit and the second refrigerantcircuit of the first embodiment;

FIG. 5 is a flowchart of an example of a process procedure of amicrocomputer in control mode A in which the refrigerating apparatus ofthe first embodiment alternately repeats a two-compressor operation anda one-compressor operation of a first compressor and a secondcompressor;

FIG. 6 is a flowchart of an example of a process procedure of themicrocomputer in control mode B in which the refrigerating apparatus ofthe first embodiment alternately repeats a one-compressor operation anda two-compressor stop of the first compressor and the second compressor;

FIG. 7 is a flowchart of an example of a process procedure of themicrocomputer in control mode C in which the refrigerating apparatus ofthe first embodiment alternately repeats a one-compressor operation ofone of the first compressor and the second compressor, and aone-compressor operation by the other of the first compressor and thesecond compressor;

FIG. 8 is a diagram of a relationship between an internal temperatureand an operational state of the first compressor and the secondcompressor when the control mode is A;

FIG. 9 is a diagram of a relationship between the internal temperatureand the operational state of the first compressor and the secondcompressor when the control mode is switched from A to B;

FIG. 10 is a diagram of a relationship between the internal temperatureand the operational state of the first compressor and the secondcompressor when the control mode is switched from B to A;

FIG. 11 is a diagram of a relationship between the internal temperatureand the operational state of the first compressor and the secondcompressor when the control mode is switched from B to C;

FIG. 12 is a diagram of a relationship between the internal temperatureand the operational state of the first compressor and the secondcompressor when the control mode is switched from A to C;

FIG. 13 is a cross-sectional view taken along A-A′ of the refrigeratingapparatus of FIG. 1;

FIG. 14A is a plan view of an exemplary arrangement of first and secondcompressors, first and second fans, and a condensing unit of arefrigerant circuit of a second embodiment and FIG. 14B is a front viewof the condensing unit of FIG. 14A;

FIG. 15 is a circuit diagram of an example of a first refrigerantcircuit and a second refrigerant circuit of a refrigerating apparatus ofa third embodiment;

FIG. 16 is a block diagram of an example of a control circuitresponsible for controlling the first refrigerant circuit and the secondrefrigerant circuit of the third embodiment;

FIG. 17 is a flowchart of an example of a process procedure of amicrocomputer in detecting and notifying of a failure by therefrigerating apparatus of the third embodiment; and

FIG. 18 is a flowchart of another example of a process procedure of themicrocomputer in detecting and notifying of a failure by therefrigerating apparatus of the third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

At least the following details will become apparent from descriptions ofthis specification and of the accompanying drawings.

First Embodiment

=Configuration of Refrigerating Apparatus=

An exemplary configuration of a refrigerating apparatus 1 of a firstembodiment will be described with reference to FIGS. 1 to 4.

FIG. 1 is a front view of an example of the refrigerating apparatus 1 ofthe first embodiment. FIG. 2 is a side view of the refrigeratingapparatus 1 of FIG. 1. FIG. 3 is a circuit diagram of an example of afirst refrigerant circuit 100 and a second refrigerant circuit 200 ofthe first embodiment. FIG. 4 is a block diagram of an example of acontrol circuit 300 responsible for controlling the first refrigerantcircuit 100 and the second refrigerant circuit 200 of the firstembodiment.

As depicted in FIGS. 1 to 4, the refrigerating apparatus 1 includes twosubstantially the same refrigerant circuits (the first refrigerantcircuit 100 and the second refrigerant circuit 200), a temperaturesensor 307 that detects an internal temperature, a microcomputer (afirst control device, a second control device, an identifying device, afirst switching device, a second switching device and a determiningdevice) 310, compressor relays (a first control device and a secondcontrol device) 305 a, 305 b, and relays (a first control device and asecond control device) 306 a, 306 b.

As depicted in FIGS. 1 and 2, the refrigerating apparatus 1 furtherincludes an inner case 5, an outer case (thermally insulating housing)2, an inner door 51 a, an outer door (thermally insulating door) 3, anda machine chamber 4, and, in the exemplary depiction of FIGS. 1 and 2,the first refrigerant circuit 100 and the second refrigerant circuit 200are almost entirely stored in the machine chamber 4 except for anevaporator 153, heat exchangers 109, 209, etc., which will be describedlater.

The inner case 5 is a substantially rectangular parallelepiped box madeof sheet steel, for example, and is separated into, for example, twostorage chambers 51 configured to store objects to be stored such asfrozen objects and biological tissues. Respective front openings of thetwo storage chambers 51 are provided with the two respective inner doors51 a made of, for example, resin that are provided in anopenable/closable manner via predetermined hinges (not depicted).

The outer case 2 is a substantially rectangular parallelepiped box madeof sheet steel, for example, and houses the machine chamber 4 and theinner case 5. Particularly, a predetermined heat insulating material(not depicted) is filled between the inner case 5 and the outer case 2.The front opening of the outer case 2 is provided with the outer door 3for taking and putting stored objects out of and into the storagechamber 51 that are attached in an openable/closable manner via hinges33. The outer door 3 is, for example, a substantially flat-plate-shapedhollow body made of sheet steel filled with a predetermined heatinsulating material (not depicted) with a rear surface thereof beingprovided with packing 34 configured to ensure air-tightness of the outercase 2 and a front surface thereof being provided with, for example, anoperation panel 32 having keys configured to set a desired internaltemperature (in the storage chamber 51) and a display configured todisplay the current internal temperature.

A handle 31 depicted in FIG. 1 enables the opening/closing operation ofthe outer door 3 by a user, etc., and has a predetermined lock mechanism(not depicted) configured to fix and unfix a state in which the outerdoor 3 is closing a front opening of the outer case 2.

<<Refrigerant Circuit>>

As depicted in FIG. 3, the first refrigerant circuit 100 includes afirst compressor 101, a pre-condenser 102 and a condenser 104 (a firstcondenser), a pressure reducer 110 (a first pressure reducer), and afirst evaporator 111 and is configured circularly with a predeterminedpipe (a first refrigerant pipe) in such a manner that a refrigerantdischarged from the first compressor 101 returns to the same compressor101 again. The first refrigerant circuit 100 further includes a flowdivider 107 that divides air and liquid, a pressure reducer 108, and aheat exchanger 109. The first refrigerant circuit 100 further includesan oil cooler 101 a in an oil pocket within the first compressor 101,includes a pipe 103 between the pre-condenser 102 and the oil cooler 101a, includes a dehydrator 106 between the condenser 104 and the flowdivider 107, and further includes a buffer 112 between a suction side ofthe first compressor 101 and the heat exchanger 109.

The first compressor 101 compresses and discharges the suckedrefrigerant to the pre-condenser 102.

The pre-condenser 102 is, for example, a pipe made of copper or aluminumprovided in a meandering manner and configured to radiate heat from therefrigerant discharged from the first compressor 101. The condenser 104is, for example, a pipe made of copper or aluminum provided in ameandering manner and configured to further radiate heat from therefrigerant outputted from the pre-condenser 102. The pre-condenser 102and the condenser 104 are integrally configured on the same tube plate,for example. A fan 105 is disposed in the vicinity of the pre-condenser102 and the condenser 104 and is configured to send air to thecondensers 102, 104 at the same time.

The flow divider 107 divides a flow of refrigerant outputted from thecondenser 104 into a liquid-phase refrigerant and a gas-phaserefrigerant, outputs the liquid-phase refrigerant to the pressurereducer 108 (capillary tube), and outputs the gas-phase refrigerant toan inner pipe 109 b of the heat exchanger 109.

The heat exchanger 109 is, for example, a double pipe made of copper oraluminum having an outer pipe 109 a and an inner pipe 109 b and coolsthe gas-phase refrigerant flowing through the inner pipe 109 b by anevaporation of the liquid-phase refrigerant, depressurized by thepressure reducer 108, in the outer pipe 109 a.

The pressure reducer 110 is, for example, a capillary tube thatdepressurizes the refrigerant that is cooled and changed into the liquidphase in the inner pipe 109 b of the heat exchanger 109 and outputs therefrigerant to the first evaporator 111.

The first evaporator 111 is, for example, a pipe made of copper oraluminum configured to evaporate the refrigerant depressurized by thepressure reducer 110 and is affixed in a thermally contacting manner tothe outer surface of the inner case 5 except for the front opening. Theinside is cooled due to the cooling effect at the time of evaporation(vaporization) of the refrigerant by the first evaporator 111. Therefrigerant evaporated and changed to the gas phase is sucked by thecompressor 101 along with the above refrigerant evaporated in the outerpipe 109 a of the heat exchanger 109.

The dehydrator 106 removes moisture contained in the refrigerant. Thebuffer 112 has a capillary tube 112 a and an expansion tank 112 b and anamount of the refrigerant circulating through the first refrigerantcircuit 100 is properly maintained by receiving the gas-phaserefrigerant on the suction side of the first compressor 101 in theexpansion tank 112 b through the capillary tube 112 a.

The second refrigerant circuit 200 includes, similarly to thedescription above, a second compressor 201, a pre-condenser 202 and acondenser 204 (a second condenser), a flow divider 207, a pressurereducer 208, a heat exchanger 209, a pressure reducer 210 (a secondpressure reducer), and a second evaporator 211 and is configuredcircularly with a predetermined pipe (a second refrigerant pipe) in sucha manner that a refrigerant discharged from the second compressor 201returns to the same compressor 201 again, and a refrigerant similar tothat described above is sealed therein. Similarly to the descriptionabove, the second refrigerant circuit 200 further includes an oil cooler201 a, a pipe 203, a dehydrator 206, and a buffer 212. The heatexchanger 209 has an outer pipe 209 a and an inner pipe 209 b. Thebuffer 212 has a capillary tube 212 a and an expansion tank 212 b. A fan205 is disposed in the vicinity of the pre-condenser 202 and thecondenser 204 and is configured to send air to the condensers 202, 204at the same time.

As depicted by dot-lines of FIGS. 1 and 2, the pipe 103 and the pipe 203described above overlap with each other as a frame pipe 151 and areattached on an inner side in a thermally contacting manner to thecircumferential portion of the front opening of the outer case 2 (afirst refrigerant pipe between the first compressor and the firstcondenser, and a second refrigerant pipe between the second compressorand the second condenser). The circumferential portion of the frontopening is a portion in close contact with the packing 34 in a statewhere the outer door 3 is closed and this portion is warmed by the framepipe 151 through which the high-temperature refrigerant discharged fromthe compressors 101, 201 flows. This prevents condensation on thecircumferential portion of the front opening and improves theair-tightness of the outer case 2.

The first evaporator 111 and the second evaporator 211 included in theevaporator 153 are arranged to cool the internal portion at the sametime. That is to say, as depicted in FIG. 2, the first evaporator 111and the second evaporator 211 are each affixed to the outer surface ofthe inner case 5 except for the front opening in a thermally contactingmanner without overlapping each other.

<<Control Circuit>>

The temperature sensor 307 is a sensor that detects the internaltemperature and that is attached to a predetermined position inside oroutside the inner case 5. The temperature sensor 307 is electricallycoupled to a control board 301 as depicted in FIG. 4 and outputs asignal indicating the detected internal temperature to the microcomputer310.

The microcomputer 310 is mounted on the control board 301 as depicted inFIG. 4 and includes a CPU 311, a ROM 312, and a RAM (an identifyingdevice) 313 to control the operation of the first compressor 101 and thesecond compressor 201 depending on the temperature detected by thetemperature sensor 307, for example. The CPU 311 executes processesrelated to such control, the ROM 312 stores programs and the like forthe CPU 311 to execute such processes, and the RAM 313 stores datanecessary for such processes. Particularly, when only one of the firstcompressor 101 and the second compressor 201 is in operation, the RAM313 stores information indicating a compressor in operation with a flag“1” linked thereto and stores information indicating a compressor atrest with a flag “0” linked thereto. The microcomputer 310 furtherincludes a timer 314 (a second timer) and a timer 315 (a first timer)configured to measure a changing time of the detected internaltemperature, operation times of the compressors 101, 201, etc. Thecontrol board 301 is supplied with electric power by a switching powersource 302. The switching power source 302 is supplied with electricpower through a three-phase power cable 303.

The compressor relay 305 a and the compressor relay 305 b are, asdepicted in FIG. 4, provided for the first compressor 101 and the secondcompressor 201, respectively, and are relays that are configured toprovide electrical connection or interruption between the correspondingcompressors 101, 201 and the three-phase power cable 303.

The relay 306 a and the relay 306 b are, as depicted in FIG. 4, providedfor the compressor relay 305 a of the first compressor 101 and thecompressor relay 305 b of the second compressor 201, respectively, andare relays configured to cause the corresponding compressor relays 305a, 305 b to perform the above connection and interruption operationsbased on a control signal outputted from the microcomputer 310.

In the control circuit 300 of the present embodiment, when a manualpower switch 304 is turned on, electric power is supplied through thethree-phase power cable 303 to the first compressor 101 and the secondcompressor 201. Fan motors 105 a, 205 a respectively rotating the fans105, 205 are supplied with electric power through the three-phase powercable 303 via predetermined relays (not depicted) controlled by themicrocomputer 310.

==Operation of Refrigerating Apparatus==

With reference to FIGS. 5 to 12, description will be made of anoperation in which the refrigerating apparatus 1 having the aboveconfiguration controls the operations of the first compressor 101 andthe second compressor 201 in accordance with the detected internaltemperature.

FIG. 5 is a flowchart of an example of a process procedure of themicrocomputer 310 in a control mode (control mode A described later) inwhich the refrigerating apparatus 1 of the first embodiment alternatelyrepeats a two-compressor operation and a one-compressor operation of thefirst compressor 101 and the second compressor 201.

FIG. 6 is a flowchart of an example of a process procedure of themicrocomputer 310 in a control mode (control mode B described later) inwhich the refrigerating apparatus 1 of the first embodiment alternatelyrepeats a one-compressor operation and a two-compressor stop of thefirst compressor 101 and the second compressor 201.

FIG. 7 is a flowchart of an example of a process procedure of themicrocomputer 310 in a control mode (control mode C described later) inwhich the refrigerating apparatus 1 of the first embodiment alternatelyrepeats a one-compressor operation of one of the first compressor 101and the second compressor 201, and a one-compressor operation of theother of the first compressor 101 and the second compressor 201.

FIG. 8 is a diagram showing a relationship between the internaltemperature and the operational state of the first compressor 101 andthe second compressor 201 for a case in which the control mode is A.

FIG. 9 is a diagram showing a relationship between the internaltemperature and the operational state of the first compressor 101 andthe second compressor 201 for a case in which the control mode isswitched from A to B.

FIG. 10 is a diagram showing a relationship between the internaltemperature and the operational state of the first compressor 101 andthe second compressor 201 for a case in which the control mode isswitched from B to A.

FIG. 11 is a diagram showing a relationship between the internaltemperature and the operational state of the first compressor 101 andthe second compressor 201 for a case in which the control mode isswitched from B to C.

FIG. 12 is a diagram showing a relationship between the internaltemperature and the operational state of the first compressor 101 andthe second compressor 201 for a case in which when the control mode isswitched from A to C.

<<Control Mode A>>

As depicted in FIG. 5, the microcomputer 310 determines whether atemperature T detected by the temperature sensor 307 (hereinafterreferred to as a “detected temperature T”) is lower than an upper limit(a first temperature) (hereinafter, “T1”) of a preset internaltemperature range (S100). If it is determined that the detectedtemperature T is lower than T1 (S100: YES), the microcomputer 310executes the process of step S100 again.

If it is determined that the detected temperature T has reached T1 (notlower than T1) (S100: NO), the microcomputer 310 starts operation of thefirst compressor 101 and the second compressor 201 (S101). While both ofthe two compressors are being operated, the detected temperature Tdecreases from T1 toward T2. It is assumed that an internal load isrelatively high due to a relatively high ambient temperature, forexample. In this case, the internal temperature decreases from T1 towardT2 by the operation of the two compressors, whereas in the case of theoperation with only one compressor, as will be described below, theinternal temperature increases from T2 toward T1.

The microcomputer 310 determines whether the detected temperature T ishigher than a lower limit (a second temperature) (hereinafter, “T2”) ofthe preset internal temperature range (S102). If it is determined thatthe detected temperature T is higher than T2 (S102: YES), themicrocomputer 310 executes the process of step S102 again.

If it is determined that the detected temperature T has reached T2 (nothigher than T2) (S102: NO), the microcomputer 310 resets the timers 314,315, causes them to start measuring time (S103), stops the one of thecompressors in operation (the first compressor 101 or the secondcompressor 201) that is linked to the flag “1” in the RAM 313 (S104),and in the RAM 313, links the flag “1” with the other of the compressorsin operation and the flag “0” with the compressor at rest (S105). Whileonly one of the two compressors 101, 201 is being operated, the detectedtemperature T increases from T2 toward T1.

The microcomputer 310 determines whether the detected temperature T islower than T2 (S106). If it is determined that the detected temperatureT is greater than or equal to T2 (S106: NO), the microcomputer 310determines whether the detected temperature T is lower than T1 (S109).

If it is determined that the detected temperature T is lower than T1(S109: YES), the microcomputer 310 determines whether a measured time tfrom the timer 315 that has started measuring time at the above stepS103 is longer than a predetermined time Y (S110). The predeterminedtime Y is a reference time for determining whether the internaltemperature has been stabilized within the preset temperature range and,specifically, if a time period during which the detected temperature Tremains between T1 and T2 is longer than the predetermined time Y, it isdetermined that the internal temperature has been stabilized within thepreset temperature range. If it is determined that the measured time tfrom the timer 315 is less than or equal to the predetermined time Y(S110: NO), the microcomputer 310 executes the process of step S109again.

If it is determined that the detected temperature T has reached T1 (notlower than T1) (S109: NO), the microcomputer 310 determines whether ameasured time t from the timer 314 that has started measuring at theabove step S103 is shorter than a predetermined time X (S111). Thepredetermined time X is a reference time required for the detectedtemperature T to increase from T2 to T1 during the operation of onecompressor that has not failed (the first compressor 101 or the secondcompressor 201), for example.

If it is determined that the measured time t from the timer 314 isgreater than or equal to the predetermined time X (S111: NO), themicrocomputer 310 executes the process of step S101 again.

If it is determined that the measured time t of the timer 314 is shorterthan the predetermined time X (S111: YES), the microcomputer 310 gives anotification to a user, etc., indicating that the compressor inoperation that is linked to the flag “1” has failed through, forexample, the display of the operation panel 32 (S112) and executes theprocess of step S101 again.

As depicted in FIG. 8, since both the first compressor 101 and thesecond compressor 201 are operated during a time period td in accordancewith the above process of the microcomputer 310, the detectedtemperature T decreases from T1 to T2.

During a subsequent time interval ts, although the second compressor 201is in operation, since the first compressor 101 is at rest, the detectedtemperature T increases from T2 to T1. As described above, the flag “1”is linked to the second compressor 201 in operation and the flag “0” islinked to the first compressor 101 at rest.

During a subsequent time interval td, since both the first compressor101 and the second compressor 201 are in operation, the detectedtemperature T decreases from T1 to T2.

During a subsequent time interval ts, although the first compressor 101is in operation, since the second compressor 201 is at rest, thedetected temperature T increases from T2 to T1. As described above,first, the second compressor 201 linked to the flag “1” is stopped, andthen the flag “1” is linked to the first compressor 101 in operation andthe flag “0” is linked to the second compressor 201 at rest.

Hereinafter, similarly, each time the detected temperature T reaches T1,both the first compressor 101 and the second compressor 201 areoperated, and each time the detected temperature T reaches T2, the firstcompressor 101 and the second compressor 201 are alternately operated(control mode A). That is to say, in control mode A, as depicted in FIG.8, with the detected temperature T being between T1 and T2, atwo-compressor operation and a one-compressor operation of the firstcompressor 101 and the second compressor 201 are alternately repeated,and the first compressor 101 and the second compressor 201 arealternately assigned to the one-compressor operation. Therefore, forexample, even in a case where the internal load has been increased dueto an increase in an ambient temperature, etc., a frequency of theperiod during which both of two compressors are in operation (td) may besuppressed since a period during which both of the two compressors 101,201 are at rest does not exist. A frequency of the period during whichonly one of them is in operation (ts) may be maintained at the samelevel between the compressors 101, 201. Therefore, the internaltemperature can be accurately controlled while suppressing the number oftimes of activation of the compressors 101, 201, and in addition, abiased deterioration between the compressors 101, 201 can be prevented.This leads to a longer lifetime and maintenance cycle of therefrigerating apparatus 1 and a reduction in power consumption due tothe activation current, etc. In the present embodiment, since the twocompressors 101 and 201 are alternately assigned to the above operationof only one compressor, each of the compressors is identified by theflag “0” or “1” stored in the RAM 313. Each of the compressors iseffectively identified with a relatively low-cost configuration usingone-bit data as above.

In control mode A, as depicted at steps S111: YES and S112 of FIG. 5,when the time required for the detected temperature T to increase fromT2 to T1 during the operation of one compressor is shorter than thepredetermined time X that is the reference time, it is determined thatthe one compressor has failed and this is notified. For example, in aplot indicating a temperature change between T1 and T2 in FIG. 8, a timeinterval ts′ of a dot-line portion is shorter than the time interval tsof other portions and this means that the increase of the internaltemperature became faster during the operation of the first compressor101, since the performance of the first compressor 101 has decreased. Asa result, since a failure of one of the two compressors 101, 201 isnotified at the time of failure, the user, etc., who has been notified,can identify the failed one and repair/replace this compressor while thecooling capacity of the two refrigerant circuits 100, 200 is maintainedat a certain level. Such a failure determination may be implementedwithout separately providing a sensor for diagnosis such as pressuresensor for each of the two compressors 101, 201. Therefore, the decreasein cooling capacity may be suppressed while suppressing themanufacturing cost of the refrigerating apparatus 1.

In the example of FIG. 5, when the microcomputer 310 determines afailure of the compressors, the time required for the detectedtemperature T of the temperature sensor 307 to increase from T2 to T1 iscompared with the predetermined time X that is a reference time, but itis not limited thereto. For example, the microcomputer (computingdevice, determining device) 310 may determine a failure by obtaining arate of change in the detected temperature during the period ofoperating only one compressor (e.g., (T1−T2)/ts) and comparing the ratewith a reference rate. For example, if a rate of increase of thedetected temperature per unit time is greater than a reference increaserate, it is determined that the corresponding compressor has failed. Inthe example of FIG. 8, since a rate of increase of the detectedtemperature during the time interval ts′ (<ts) is (T1−T2)/ts′ and a rateof increase of the detected temperature during the time interval ts is(T1−T2)/ts it is determined that the first compressor 101 correspondingto the former of a greater value has failed.

Since at least one of the compressors 101, 102 is always operated withthe operation in control mode A as above, the high-temperaturerefrigerant always flows through the above-mentioned frame pipe 151 andthe condensation on the circumferential portion of the front opening ofthe outer case 2 is efficiently prevented. This further improves theair-tightness in the outer case 2.

<<Switching of Control Mode from A to B>>

If it is determined that the detected temperature T is lower than T2 atthe above-mentioned step S106 of FIG. 5 (S106: YES), the microcomputer310 determines whether the detected temperature T is higher than T4(<T2) (S107).

If it is determined that the detected temperature T is higher than T4(S107: YES), the microcomputer 310 executes the process of step S107again.

If it is determined that the detected temperature T has reached T4 (nothigher than T4) (S107: NO), the microcomputer 310 stops the compressorin operation that is linked to the flag “1” (S108) and executes theprocess of control mode B described below. In other words, even after aswitching from the operation of the two compressors 101, 201 to theoperation of one compressor, if the detected temperature T decreases toT4 (a fourth temperature), which is lower than T2, due to, for example,a decrease in the ambient temperature, control mode A is switched overto control mode B in which both of the two compressors are stopped.

As depicted in FIG. 6, the microcomputer 310 determines whether thedetected temperature T from the temperature sensor 307 is lower than T1(S200). If it is determined that the detected temperature T is lowerthan T1 (S200: YES), the microcomputer 310 executes the process of stepS200 again. As described above, while both of the two compressors 101,201 are at rest, the detected temperature T increases from T4 toward T1.

If it is determined that the detected temperature T has reached T1 (notlower than T1) (S200: NO), the microcomputer 310 resets the timers 314,315, causes them to start measuring time (S201), starts operation of thecompressor at rest (the first compressor 101 or the second compressor201) that is linked to the flag “0” (S202), and links the flag “1” tothis compressor in operation and the flag “0” to the compressor at rest(S203). While only one of the two compressors 101, 201 is in operation,the detected temperature T decreases from T1 to T2. Here, it is assumedthat the internal load is relatively small due to a relatively lowambient temperature as described above. In this case, the internaltemperature decreases from T1 toward T2 by operating only onecompressor, and the internal temperature increases from T2 toward T1 bystopping the two compressors.

The microcomputer 310 determines whether the detected temperature T ishigher than T1 (S204). If it is determined that the detected temperatureT is lower than or equal to T1 (S204: NO), the microcomputer 310determines whether the detected temperature T is higher than T2 (S206).

If it is determined that the detected temperature T is higher than T2(S206: YES), the microcomputer 310 determines whether a measured time tfrom the timer 315 that has start measuring at above step S201 is longerthan the predetermined time Y (S207). As described above, thepredetermined time Y is a reference time for determining whether theinternal temperature has been stabilized within the preset temperaturerange. This predetermined time Y may be the same as or different fromthe above predetermined time Y. If it is determined that the measuredtime t from the timer 315 is less than or equal to the predeterminedtime Y (S207: NO), the microcomputer 310 executes the process of stepS206 again.

If it is determined that the detected temperature T has reached T2 (notlower than T2) (S206: NO), the microcomputer 310 stops the compressor inoperation that is linked to the flag “1” (S208) and determines whether ameasured time t from the timer 314 that has started measuring at theabove step S201 is longer than a predetermined time X′ (S209). Thepredetermined time X′ is, for example, a reference time required for thedetected temperature T to decrease from T1 to T2 by the operation of onecompressor having no failure.

If it is determined that the measured time t by the timer 314 is shorterthan or equal to the predetermined time X′ (S209: NO), the microcomputer310 executes the process of step S200 again.

If it is determined that the measured time t by the timer 314 is longerthan the predetermined time X (S209: YES), the microcomputer 310 gives anotification to a user, etc., to indicate that there is a failure in thecompressor in operation that is linked to the flag “1”, for example,through the display of the operation panel 32 (S210) and executes theprocess of step S200 again.

As depicted in FIG. 9, since both the first compressor 101 and thesecond compressor 201 are operated during a time interval td inaccordance with the above process of the microcomputer 310, the detectedtemperature decreases from T1 to T2 (time interval td).

Although the first compressor 101 at rest during a subsequent timeinterval ts′, since the second compressor 201 is in operation, thedetected temperature T decreases from T2 to T4. That is to say, as hasbeen described above, even after being switched from the operation ofthe two compressors 101, 201 to the operation of one compressor, thedetected temperature T will decrease to T4, which is lower than T2, dueto, for example, a decrease in the ambient temperature. The process ofcontrol mode A has been executed up to this point. As described above,the flag “1” is linked to the second compressor 201 in operation and theflag “0” is linked to the first compressor 101 at rest.

Since both the first compressor 101 and the second compressor 201 are atrest during a subsequent time period tn, the detected temperature Tincreases from T4 to T1. The process of control mode B is executed fromthis point.

Although the second compressor 201 is at rest during a subsequent timeinterval ts, since the first compressor 101 is in operation, thedetected temperature T decreases from T1 to T2. As described above, thesecond compressor 201 linked to the flag “1” is first stopped, and then,the flag “1” is linked to the first compressor 101 in operation and theflag “0” is linked to the second compressor 201 at rest.

Since both the first compressor 101 and the second compressor 201 are atrest during the subsequent time interval tn, the detected temperature Tincreases from T2 to T1.

Although the first compressor 101 is at rest during the subsequent timeinterval ts, since the second compressor 201 is in operation, thedetected temperature T decreases from T1 to T2. As described above, thefirst compressor 101 linked to the flag “1” is first stopped and thenthe flag “1” is linked to the second compressor 201 in operation and theflag “0” is linked to the first compressor 101 at rest.

Similarly, each time the detected temperature T reaches T1, one of thefirst compressor 101 and the second compressor 201 is alternatelystarted to operate continuously until the detected temperature T reachesT2 (control mode B). That is to say, in control mode B, as depicted inFIG. 9, while the detected temperature is T between T1 and T2, theone-compressor operation of one of the first compressor 101 and thesecond compressor 201 and the stop of the both compressors arealternately repeated and the first compressor 101 and the secondcompressor 201 are alternately assigned to the one-compressor operation.Therefore, if the internal load is reduced due to a decrease in ambienttemperature, etc., while the refrigerating apparatus 1 is operated incontrol mode A, the internal temperature may accurately be controlled byswitching to the operation in control mode B. A frequency of the period(ts) of operating only one compressor may be maintained at the samelevel for each of the compressors 101, 201. Therefore, the internaltemperature may be accurately controlled while the number of times ofactivation of the compressors 101, 201 is suppressed, and a biaseddeterioration between the compressors 101 and 201 can be prevented. Thisleads to a longer lifetime and maintenance cycle of the refrigeratingapparatus 1 and the reduction, etc., of power consumption due to theactivation current.

In control mode B, as depicted at steps S209: YES and S210 of FIG. 6,when the time required for the detected temperature T to increase fromT1 to T2 during the operation of one compressor is longer than thepredetermined time X′, which is the reference time, it is determined andnotified that the one compressor has failed. For example, in a plotindicating temperature changes between T1 and T2 in FIG. 9, a timeinterval ts″ of a dot-line portion is longer than the time interval tsof other portions and this means that the increase of the internaltemperature became slower during the operation of the second compressor201 due to a decrease in the capacity of the second compressor 201. As aresult, since the notification is made when one of the two compressors101, 201 has failed, the notified user, etc., can identify the failedone and repair/replace this compressor while the cooling capacity of thetwo refrigerant circuits 100, 200 is maintained at a certain level. Sucha failure determination may be implemented without separately providinga sensor for diagnosis, such as pressure sensor, for each of the twocompressors 101, 201. Therefore, the decrease of the cooling capacitymay be suppressed while suppressing the manufacturing cost of therefrigerating apparatus 1.

In the example of FIG. 6, when the microcomputer 310 determines afailure of the compressors, although the time required for the detectedtemperature T of the temperature sensor 307 to decrease from T1 to T2 iscompared with the predetermined time interval X′ that is a referencetime interval, it is not limited thereto. For example, the microcomputer(computing device, determining device) 310 may determine a failure byobtaining a rate of change in the detected temperature during the periodof operating only one compressor (e.g., (T1−T2)/ts) and comparing therate with a reference rate. For example, if a rate of decrease of thedetected temperature per unit time is smaller than a reference rate ofdecrease, it is determined that the corresponding compressor has failed.In the example of FIG. 9, since a rate of decrease of the detectedtemperature during the time interval ts″ (>ts) is (T1−T2)/ts″ and a rateof decrease of the detected temperature during the time interval ts is(T1−T2)/ts, it is determined that the second compressor 201corresponding to the former smaller value has failed.

<<Switching of Control Mode from B to A>>

If it is determined that the detected temperature T is higher than T1 atabove step S204 of FIG. 6 (S204: YES), the microcomputer 310 determineswhether the detected temperature T is lower than T3 (>T1) (S205).

If it is determined that the detected temperature T is lower than T3(S205: YES), the microcomputer 310 executes the process of step S205again.

If it is determined that the detected temperature T has reached T3 (notlower than T3) (S205: NO), the microcomputer 310 executes the process ofcontrol mode A. That is to say, even after a switch over from the stopof the two compressors 101, 201 to the operation of one compressor, ifthe detected temperature T increases to T3 (a third temperature), whichis higher than T1, due to, for example, an increase in ambienttemperature control mode B is switched over to control mode A in whichboth of the two compressors are operated.

As depicted in FIG. 10, the operation of the refrigerating apparatus 1is performed in control mode B during a first time interval (ts″+tn+ts′)and, during a time interval ts′ of the first time interval, the detectedtemperature T increases to T3 even though the second compressor 201 isin operation. Therefore, the refrigerating apparatus 1 is subsequentlyoperated in control mode A. As a result, even if the internal load isincreased due to, for example, an increase in ambient temperature, etc.,while the refrigerating apparatus 1 is being operated in control mode B,the internal temperature may be accurately controlled by switching overto the operation in control mode A.

<<Switching of Control Mode from B to C>>

At above step S207 of FIG. 6, if it is determined that the measured timet of the timer 315 is longer than the predetermined time Y (S207: YES),the microcomputer 310 executes the following process of control mode C.That is to say, when a time period during which the detected temperatureT is between T1 and T2 is longer than the predetermined time Y, it isdetermined that the internal temperature has been stabilized within thepreset temperature range.

As depicted in FIG. 7, the microcomputer 310 resets the timer 315,causes it to start measuring time (S300), stops the one compressor inoperation which is linked to the flag “1”, and starts operating theother compressor at rest which is linked to the flag “0” (S301). Then,the microcomputer 310 links the flag “1” to the compressor that hasstarted operating and links the flag “0” to the compressor that has cometo a rest (S302).

The microcomputer 310 determines whether the measured time t from thetimer 315 which has started measuring at the above step S300 has reachedthe predetermined time Y (S303).

If it is determined that the measured time t from the timer 315 hasreached the predetermined time Y (S303: NO), the microcomputer 310executes the process of step S300 again.

While the detected temperature T is slowly decreasing from T1 withoutreaching T2 during the first time zone ts″ of FIG. 11, the operation ofthe second compressor 201 is continued until the operation time reachesthe predetermined time Y (i.e., until ts″=Y is satisfied). As describedabove, the flag “1” is linked to the second compressor 201 in operationand the flag “0” is linked to the first compressor 101 at rest.

When the operation time of the second compressor 201 reaches thepredetermined time Y, the second compressor 201 is stopped and theoperation of the first compressor 101 is started at the same time. Asdescribed above, first, the second compressor 201 linked to the flag “1”is stopped, and then, the flag “1” is linked to the first compressor 101in operation and the flag “0” is linked to the second compressor 201 atrest.

Subsequently, the first compressor 101 and the second compressor 201 arealternately operated for each of the predetermined times Y. Therefore, afrequency of the period of operating only one compressor may bemaintained at the same level for each of the compressors 101, 201. Thisleads to a longer lifetime and maintenance cycle of the refrigeratingapparatus 1.

Since the two compressors 101, 201 are alternately operated in controlmode C, a failed compressor may easily be identified from above changesin the detected temperature, for example. The operation time of each ofthe compressors 101, 201 in control mode C is not limited to the abovepredetermined time Y and may be different from the predetermined time Y,for example.

On the other hand, if it is determined that the measured time t from thetimer 315 has not reached the predetermined time Y at step S303, first,the microcomputer 310 determines whether the detected temperature T fromthe temperature sensor 307 is lower than T1 (S304) and then whether thedetected temperature T is higher than T2 (S305). If it is determinedthat the detected temperature T has reached T1 (S304: NO), themicrocomputer 310 executes the process of step S100 of FIG. 5. Thismeans that a switch over to the mode A is performed, since the coolingcapacity of only one of the compressors has become insufficient. If itis determined that the detected temperature T has reached T2 (S305: NO),the microcomputer 310 executes the process of step S200 of FIG. 6. Thismeans that a switch over to the mode B is performed since the coolingcapacity is sufficient with only one of the compressors.

<<Switching of Control Mode from A to C>>

At above step S110 of FIG. 5, if it is determined that the measured timet from the timer 315 is longer than the predetermined time Y (S110:YES), the microcomputer 310 executes the following process of controlmode C. That is to say, when a time period during which the detectedtemperature T is between T1 and T2 is longer than the predetermined timeY, it is determined that the internal temperature has been stabilizedwithin the preset temperature range.

The process procedures of the microcomputer 310 in the operation ofcontrol mode C are the same as those described above (see FIG. 7).

While the detected temperature T is slowly increasing from T2 withoutreaching T1 during the first time zone ts″ of FIG. 12, the operation ofthe first compressor 101 is continued until the operation time reachesthe predetermined time Y (i.e., until ts″=Y is satisfied). As describedabove, the flag “1” is linked to the first compressor 101 in operationand the flag “0” is linked to the second compressor 201 at rest.

When the operation time of the first compressor 101 reaches thepredetermined time Y, the first compressor 101 is stopped and theoperation of the second compressor 201 is started at the same time. Asdescribed above, first, the second compressor 201 linked to the flag “1”is stopped and then the flag “1” is linked to the second compressor 201in operation and the flag “0” is linked to the first compressor 101 atrest.

Subsequently, the first compressor 101 and the second compressor 201 arealternately operated for each of the predetermined times Y. Therefore, afrequency of the period of operating only one compressor can bemaintained at the same level for the compressors 101, 201. This leads toa longer lifetime and maintenance cycle of the refrigerating apparatus1.

Since the two compressors 101, 201 are alternately operated in controlmode C, a failed compressor can be easily identified from, for example,above changes in the detected temperature. The operation time of each ofthe compressors 101, 201 in control mode C is not limited to the abovepredetermined time Y and may be different from the predetermined time Y,for example.

Among control modes A, B, and C described above, the currently performedmode is, for example, stored in the RAM 313 as a flag (e.g., 0, 1, 2)that is preliminarily linked to each of the modes. The microcomputer 310refers to this flag on a timely basis.

Other Embodiments

The above embodiments of the present invention are simply forfacilitating the understanding of the present invention and are not inany way to be construed as limiting the present invention. The presentinvention may variously be changed or altered without departing from itsspirit and encompass equivalents thereof.

In the above-mentioned embodiment, in order to identify which of thefirst compressor 101 and the second compressor 201 is in operation, theRAM 313 stores the flag “1” linked to information indicative of theoperated compressor and the flag “0” linked to information indicative ofthe compressor at rest, but it is not limited thereto. For example, theoperation state of the compressors 101, 201 may be identified through apredetermined means for detecting whether the compressor relays 305 a,305 b and the relays 306 a, 306 b respectively provided for thecompressors 101, 201 are connected or interrupted.

In the above-mentioned embodiment, the display of the operation panel 32is used as a means that notifies of a failure of the compressors 101,201, but it is not limited thereto. Such a notifying means may basicallybe any means as long as it is the means that notifies a user, etc., ofwhich compressor has failed.

In the above embodiment, the first refrigerant circuit 100 and thesecond refrigerant circuit 200 shown in FIG. 3 are used as tworefrigerant circuits, it is not limited thereto. Each of the refrigerantcircuits may basically be any refrigerant circuit as long as therefrigerant circuit includes the compressor, the condenser, the pressurereducer, and the evaporator connected circularly with refrigerant pipesand the refrigerant discharged from the compressor is condensed by thecondenser and then evaporate by the evaporator to achieve a coolingeffect.

Second Embodiment

A refrigerating apparatus is known that includes two refrigerantcircuits having compressors, condensers, pressure reducers, andevaporators.

Since the refrigerant is compressed, condensed and then evaporated ineach of the two refrigerant circuits, an object to be cooled that is,for example, in thermal contact with the two evaporators in common isrefrigerated.

Such a refrigerating apparatus includes fans configured to cool each ofthe condensers to facilitate the heat exchange in the respectivecondensers of the two refrigerant circuits. In other words, the twocondensers included in the two refrigerant circuits are respectively andindividually cooled by the two fans.

In the above refrigerating apparatus, in a case where one of the twofans stops due to a failure of a fan motor, a heat exchange amountbetween refrigerant and air is decreased in the condenser correspondingto this fan. Therefore, a condensation amount of the refrigerant isdecreased in the condenser and an endothermic amount (evaporationamount) of the refrigerant is decreased in the evaporator. This causes adecrease in the cooling capacity of the refrigerant circuit.

Accordingly, in a case where the cooling capacity has decreased in therefrigerant circuit having the condenser corresponding to the stoppedfan, even though the refrigerating apparatus has two refrigeratingcircuits, it becomes substantially equivalent to the case in which therefrigerating apparatus includes only one refrigerant circuit, and thecooling capacity is reduced by half.

In a case where one of the fans fails and stops, the refrigerantpressure is increased on a high-pressure side, and thus a protectiondevice is activated and stops the compressor in operation. After thefailure of the fan, the cooling capacity of the refrigerating apparatusis decreased to the level equivalent to that of the case of includingonly one refrigerant circuit.

It is therefore the object of the present invention to maintain thecooling capacity of the refrigerating apparatus higher than the case ofthe operation with only one refrigerant circuit even if one of the twofans stops during the operation of the two refrigerant circuits of therefrigerating apparatus.

=Refrigerating Apparatus=

A refrigerating apparatus of a second embodiment has the sameconstituents as the constituents depicted in FIGS. 1 and 2 of the firstembodiment and explanations for the same reference numerals will beomitted. The operation panel 32 is electrically connected, through apredetermined wiring (not depicted), to a control unit (e.g., thecontrol board 301) integrally controlling, for example, the firstcompressor 101 and the second compressor 201, and a predeterminedtemperature sensor (not depicted) provided in the storage chamber 51.

In the second embodiment, as depicted in FIG. 13, the outer surface ofthe inner case 5 and the inner surface of the outer case 2 are spaced bya predetermined distance and the gap therebetween is filled with a heatinsulating material 6 to enhance the refrigerating efficiency of theinner case 5. The insulating material 6 is for example, a polyurethaneresin insulating material and a vacuum heat insulating material made ofglass wool. As depicted in FIG. 13, the inside of the outer door 3 isalso filled with the insulating material 6 and, therefore, theinsulation is provided between the inner door 51 a and the outer door 3.As depicted in FIGS. 1 and 2, the inner case 5 and the machine chamber 4are spaced by a predetermined distance and the insulation is provided ina similar way as above.

=Refrigerant Circuit=

A refrigerant circuit of a second embodiment has the same constituentsas a refrigerant circuit 150 depicted in FIG. 3 of the first embodimentand a control circuit controlling the refrigerant circuit of the secondembodiment has substantially the same constituents as the controlcircuit 300 of the first embodiment. In other words, in the case of thefirst embodiment, the temperature sensor 307 is connected to the controlboard 301 whereas, in the case of the second embodiment, the controlboard 301 is, instead of the temperature sensor 307, connected to afirst compressor temperature sensor 307A, a second compressortemperature sensor 307B, a first temperature sensor 307C, a secondtemperature sensor 307D, a first sensor 307E, and a second sensor 307F.Explanations for the same reference numerals will be omitted.

An exemplary configuration of the refrigerant circuit 150 of the secondembodiment will be described with reference to FIGS. 3 and 4 of thefirst embodiment and FIGS. 14A and 14B of the second embodiment. FIG.14A is a plan view of an exemplary arrangement of the first compressor101 and the second compressor 201, the first fan 105 and the second fan205, and a condensing unit 152 of the refrigerant circuit 150 of FIG. 3.This plan view is a diagram taken along B-B′ of FIG. 1 when the circuitis viewed in the direction of arrows. FIG. 14B is a front view of thecondensing unit 152 of FIG. 14A. Dotted lines in this plan view is adiagram taken along C-C′ of FIG. 14A when the pre-condenser 102 and thecondenser 104 are viewed in the direction of arrows.

In the second embodiment, the refrigerant used in the refrigerantcircuit 150 is a zeotropic refrigerant mixture including R245fa, R600,R23, and R14, for example. R245fa denotes pentafluoropropane(CHF₂CH₂CF₃) and the boiling point is +15.3° C. (degrees Celsius). R600denotes n-butane (n-C₄H₁₀) and the boiling point is −0.5° C. R23 denotestrifluoromethane (CHF₃) and the boiling point is −82.1° C. R14 denotestetrafluoromethane (CF₄) and the boiling point is −127.9° C.

R600 has a high boiling point (evaporating temperature) and easilycontain oil, water, etc. R245fa is a refrigerant mixed with R600, whichis combustible, at a predetermined ratio (e.g., a ratio of R245fa toR600 is 7:3) to make R600 incombustible.

In the first refrigerant circuit 100, the refrigerant compressed by thefirst compressor 101 radiates heat, condenses, turns to a liquid phasein the pre-condenser 102 and the condenser 104, is then subjected to awater removal process by the dehydrator 106, and is divided by the flowdivider 107 into a refrigerant in a liquid state (mainly R245fa and R600having higher boiling points) and a refrigerant in a gas state (R23,R14). In the second embodiment, the refrigerant that has radiated heatin the pre-condenser 102 cools the oil in the first compressor 101 withthe oil cooler 101 a and then radiates heat again in the condenser 104.

The divided refrigerant in the liquid state (mainly R245fa, R600) isdepressurized by the pressure reducer 108 and evaporated in the outerpipe 109 a of the heat exchanger 109.

While passing through the inner pipe 109 b of the heat exchanger 109,the divided refrigerant in the gas state (R23, R14) is cooled andcondensed into the liquid state due to the heat of evaporation of therefrigerant (R245fa, R600) that has evaporated in the above outer pipe109 a and the gas-phase refrigerant (R23, R14) returned from the firstevaporator 111 described later. The refrigerant that has not evaporatedin the first evaporator 111 is evaporated at this point.

The same applies to the second refrigerant circuit 200.

As described above, since the boiling points of R245fa, R600, R23, andR14 are about 15° C., about 0° C., about −82° C., and about −128° C.,respectively, the refrigerant circuits 100 and 200 cools R23 and R14 ofthe zeotropic refrigerant mixture with an evaporating effect of R600 andguides and evaporates R23 and R14 turned to the liquid phase into theevaporating unit 153 (the first evaporator 111 and the second evaporator211), and thus the object to be cooled can be cooled to a temperaturecorresponding to the boiling points of R23 and R14 (e.g., about −82° C.to −128° C.), for example. The non-evaporated refrigerant in the firstevaporator 111 and the second evaporator 211 is evaporated at the heatexchangers 109, 209.

<<Condensing Unit, Fans and Compressor>>

As depicted in FIG. 14A, the refrigerating apparatus 1 is provided withthe first fan 105 and the second fan 205 configured to cool thepre-condenser 102 and the condenser 104 of the first refrigerant circuit100 and the pre-condenser 202 and the condenser 204 of the secondrefrigerant circuit 200. The first fan 105 and the second fan 205 of thesecond embodiment are propeller air blowers having the fan motors 105 aand 205 a, respectively. The first fan 105 and the second fan 205 form asingle air passage through which the air flow, with a housing making upthe machine chamber 4 serving as a fan casing.

As depicted in FIG. 14A, the pre-condenser 102 and the condenser 104 ofthe first refrigerant circuit 100 and the pre-condenser 202 and thecondenser 204 of the second refrigerant circuit 200 are bundled by thecommon tube plate 152 a of a substantially rectangular parallelepipedshape and make up the condensing unit 152. As depicted in FIG. 14B, eachof the pre-condenser 102 and the condenser 104 forms a refrigerant flowchannel meandering in parallel with the substantially rectangular frontsurface of the condensing unit 152. This configuration is similar to thepre-condenser 202 and the condenser 204 and these four condensers 102,104, 202, 204 are formed as parallel lines (four lines) in thecondensing unit 152 from the front surface to the rear surface inparallel with the front surface of the substantially rectangular shape.Each of the four lines of the condensers 102, 104, 202, 204 is disposedto face both of the first fan 105 and the second fan 205 that aredisposed in parallel behind the condensing unit 152. That is to say, inthe substantially rectangular parallelepiped condensing unit 152, thepre-condenser 102 and the condenser 104 depicted by dot-lines in FIG.14B extend from the left end to the right end of the plane of FIG. 14B,meander by turning back at each end portion, and extend from the upperside to the lower side of the plane of FIG. 14B. The pre-condenser 202and the condenser 204 that are not depicted in FIG. 14B have a similarshape. The pre-condenser 102 and the condenser 104 are disposed inparallel in the second and fourth lines from the lower side of the planeof FIG. 14A in the substantially rectangular parallelepiped condensingunit 152 and the pre-condenser 202 and the condenser 204 are disposed inparallel in the first and third lines from the lower side of the planeof FIG. 14A in the substantially rectangular parallelepiped condensingunit 152.

The pre-condenser 102 and the condenser 104 are not limited to such aconfiguration and may, in the substantially rectangular parallelepipedcondensing unit 152, extend from the left end of the plane of FIG. 14Bto a position beyond the horizontal center portion of the condensingunit 152, for example, and may meander by turning back at each of theleft end and the position beyond the horizontal center portion. That isto say, the pre-condenser 102 and the condenser 104 may form a shapesubstantially entirely facing the first fan 105 and partially facing thesecond fan 205, for example. The same applies to the pre-condenser 202and the condenser 204.

As depicted in FIG. 14A, both the first fan 105 and the second fan 205are disposed in parallel to face the rear surface of the condensing unit152. The first compressor 101 is disposed behind the first fan 105 andthe second compressor 201 is disposed behind the second fan 205. Thecondensing unit 152, the first fan 105 and the second fan 205, as wellas the first compressor 101 and the second compressor 201 depicted inFIG. 14A are disposed on the same horizontal plane.

With such an arrangement, in the second embodiment, for example, thefirst fan 105 forms an air passage that lies along substantially thewhole of the rear surface of the condensing unit 152 and, via the firstfan 105, covers substantially the whole of the first compressor 101including at least a portion of the second compressor 201. Similarly, inthe second embodiment, the second fan 205 forms an air passage that liesalong substantially the whole of the rear surface of the condensing unit152 and, via the second fan 205, covers substantially the whole of thesecond compressor 201 including at least a portion of the firstcompressor 101.

In the second embodiment, a direction of blowing air by the first fan105 and the second fan 205 is a direction from the front side to therear side of the refrigerating apparatus 1 (an outline arrow of FIG.14A).

<<Control Circuit>>

The microcomputer 310 in the control board 301 outputs a control signalfor opening/closing each of two the relays 306 a, 306 b and outputs acontrol signal for starting or stopping the operation of the fan motors105 a, 205 a based on detection signals from the first compressortemperature sensor 307A and the second compressor temperature sensor307B. The first compressor temperature sensor 307A detects thetemperature of the first compressor 101 and the second compressortemperature sensor 307B detects the temperature of the second compressor201.

When it is detected that the temperature of the first compressor 101detected by the first compressor temperature sensor 307A has exceeded apredetermined temperature during the operation of the first compressor101, the microcomputer 310 operates the compressor relay 305 acorresponding to the first compressor 101, through the relay 306 acorresponding to the first compressor 101, to interrupt the input of thethree-phase voltage to the first compressor 101. This provides thefunction as a protection circuit concerning a temperature increase ofthe first compressor 101, and the same applies to the second compressor201. When the power switch 304 is turned on, the first compressor 101and the second compressor 201 are supplied with electric power throughthe three-phase power cable 303 to start a refrigerant compressionoperation. Although not depicted, for example, the microcomputer 310compares the internal temperature detected by the first temperaturesensor 307C with a temperature determined in advance and controls therotation speed of a motor (not depicted) of the first compressor 101depending on the comparison result. This controls the compressionability of the first compressor 101 depending on the internaltemperature and the same applies to the second compressor 201. The firsttemperature sensor 307C and the second temperature sensor 307D may bethe same sensor.

As depicted in FIG. 4, the microcomputer 310 controls the fan motors 105a, 205 a separately from the control of the first compressor 101 and thesecond compressor 201 described above. Although not depicted, themicrocomputer 310 stops the operation of the fan motor 105 a when it isdetected that the temperature of the first fan 105 detected by the firstsensor 307E has exceeded a temperature determined in advance, forexample. This provides the function as a protection circuit related to atemperature increase of the first fan 105 and the same applies to thesecond fan 205. The first sensor 307E and the second sensor 307F may beimplemented by sharing a single sensor provided in the vicinity of bothof the fan motors 105 a, 205 a, for example.

In the second embodiment, for example, even if there is a failure in thefan motors 105 a, 205 a, the first compressor 101 and the secondcompressor 201 in operation continue the refrigerant compressionoperation irrespectively.

According to the configuration described above, since the first andsecond condensers are disposed in an area in which the air passageformed by the first fan 105 and the air passage formed by the second fan205 are identical even if one of the fans stops blowing air, the bothcondensers are cooled by the air blown from the other fan. The firstcompressor 101 is disposed to face the first fan 105 and the secondcompressor 201 is disposed to face the second fan 205.

The first fan 105 and the second fan 205 located in parallel aredisposed to face the first compressor 101 and the second compressor 201,respectively, in the same air passage, if one of the first fan 105 andthe second fan 205 rotates, even the compressor (the first compressor101 or the second compressor 201) not facing this fan at least partiallyreceives air and is cooled.

Further, the control circuit 300 is configured such that, for example,even if there is a failure in the fan motors 105 a, 205 a, the firstcompressor 101 and the second compressor 201 in operation continue theoperation irrespectively. That is to say, the first fan 105 and thesecond fan 205 rotate separately from the first compressor 101 and thesecond compressor 201.

Therefore, even if one of the fans (the first fan 105 or the second fan205) is stopped during the operation of the refrigerating apparatus 1,the cooling capacity is maintained at a cooling capacity exceeding thecapacity by only one refrigerant circuit.

As above, the refrigerating apparatus 1 of the second embodiment atleast includes the first refrigerant circuit 100 having the firstcompressor 101, the first condenser (such as the pre-condenser 102 andthe condenser 104), and the first evaporator 111, the second refrigerantcircuit 200 having the second compressor 201, the second condenser (suchas the pre-condenser 202 and the condenser 204), and the secondevaporator 211, the first fan 105 operating separately from the firstcompressor 101 and the second compressor 201, and the second fan 205operating separately from the first compressor 101 and the secondcompressor 201, and the first and second condensers as well as the firstfan 105 and the second fan 205 may be arranged in such a manner that ina case where one of the fans (the first fan 105 or the second fan 205)stops while both the first refrigerant circuit 100 and the secondrefrigerant circuit 200 are in operation, the other fan cools both thefirst condenser and the second condenser.

With this refrigerating apparatus 1, even if one of the first fan 105and the second fan 205 stops during the operation of the firstrefrigerant circuit 100 and the second refrigerant circuit 200, theoperation of both of the refrigerant circuits 100, 200 are continuedwhile the other fan is cooling both the first and second condensers.Therefore, even if one of the fans stops, the cooling capacity of therefrigerating apparatus 1 including the two refrigerant circuits 100,200 can be maintained higher than that of a case in which only onerefrigerant circuit is provided, for example.

In the above refrigerating apparatus 1, the first and second compressorsand the first fan 105 and the second fan 205 are arranged in such amanner that in a case where one of the fans stops while both the firstrefrigerant circuit 100 and the second refrigerant circuit 200 areoperating, the other fan cools both the first compressor 101 and thesecond compressor 201.

With this refrigerating apparatus 1, even if one of the fans stopsduring the operation of the first refrigerant circuit 100 and the secondrefrigerant circuit 200, the other fan cools the first compressor 101and the second compressor 201 and the increase in temperature of thecompressors can be suppressed.

In the above refrigerating apparatus 1, the first fan 105 and the secondfan 205 are arranged in parallel and the first and second condensers arearranged to face both the first fan 105 and the second fan 205.

With this refrigerating apparatus 1, since the first and secondcondensers are disposed in the area where the air passage formed by thefirst fan 105 and the air passage formed by the second fan 205 are thesame, even if one of the fans stops blowing air, the both condensers arecooled by the air blown from the other fan.

Other Embodiments

The above embodiments of the present invention are simply forfacilitating the understanding of the present invention and are not inany way to be construed as limiting the present invention. The presentinvention may variously be changed or altered without departing from itsspirit and encompass equivalents thereof.

In the above embodiment, the first refrigerant circuit 100 and thesecond refrigerant circuit 200 are substantially identical unitaryrefrigerant circuits, but it is not limited thereto, and, for example,the refrigerant circuits may have configurations, capacities, etc., thatare different from each other.

In the above embodiment, the heat exchangers 109, 209 are of thedouble-pipe type having the outer pipes 109 a, 209 a and the inner pipes109 b, 209 b, but it is not limited thereto, and, for example, the heatexchangers may be of the multi-pipe type or the plate type.

In the above embodiment, the refrigerant is a zeotropic refrigerantmixture including R245fa, R600, R23, and R14, but it is not limitedthereto. For example, R245fa and R600 may be those having a boilingpoint at which they come to a substantially liquid state when condensedby the condensing unit 152. For example, R23 and R14 may be thoserefrigerants having a boiling point at which they remain in asubstantially gaseous state when condensed by the condensing unit 152but come to a substantially liquid state in the heat exchangers 109,209.

In the above embodiment, the condensing unit 152, the first fan 105, andthe second fan 205 are disposed on the same horizontal plane, but it isnot limited thereto. For example, the disposition planes may be locatedat different levels as long as the fans (the first fan 105 and thesecond fan 205) are located and oriented in such a manner that air canbe blown to the condensing unit 152.

In the above embodiment, the first fan 105 and the second fan 205 arepropeller air blowers having the fan motors 105 a and 205 a,respectively, but it is not limited thereto. The fans may basically havea predetermined configuration for cooling the condensing unit 152.

The refrigerating apparatus of the second embodiment is applicable tothe refrigerating apparatus of the first embodiment.

Third Embodiment

A refrigerating apparatus is known that includes two refrigerantcircuits having compressors, condensers, pressure reducers, andevaporators. In each of the two refrigerant circuits, the refrigerantdischarged from the compressor is cooled and liquefied by the condenserand, via the pressure reducer, evaporated by the evaporator, and thus,for example, an internal portion of a cold storage cabinet in thermalcontact with the two evaporators in common is cooled.

This refrigerating apparatus includes fans configured to facilitate thecooling of the refrigerant for the respective condensers of the tworefrigerant circuits. The two respective fans individually blow air tothe two condensers included in the two refrigerant circuits tofacilitate the heat exchange between the ambient air and therefrigerant.

Since the role of the fans is important for the heat exchange of thecondenser as above, the refrigerating apparatus always monitors whethera fan motor that rotates each of the fans has failed. For example, therefrigerating apparatus detects respective temperatures of the outletportions of the two condensers by a predetermined temperature sensorand, for example, in a case where the temperature of the outlet portionof one condenser has exceeded a predetermined temperature, it isdetermined that the corresponding fan motor has failed. Such a failuredetecting method is based on a relationship between the fans and thecondensers that when the fan stop due to a failure in the fan motor, thetemperature of the outlet portion is increased since the condenser isnot sufficiently cooled. When a failure of the fan motor is detected,the refrigerating apparatus notifies a user, etc., of the failurethrough a predetermined notifying means.

In the above refrigerating apparatus, for example, in a case where oneof the two fans has stopped due to a failure of a fan motor, a heatexchange amount between refrigerant and air is reduced in the condenserthat should receive air blown by this fan under normal conditions and,therefore, a condensation amount of the refrigerant is reduced in thecondenser. This is problematic since an endothermic amount (evaporationamount) of the refrigerant is reduced in the evaporator of thecorresponding refrigerant circuit, resulting in reduction of the coolingcapacity of the refrigerating apparatus.

As described above, in a case where the increase in temperature of theoutlet portion of the condenser is taken into consideration indetermining that the corresponding fan motor has failed, since thecooling capacity of the refrigerating apparatus has already been reducedat the time of detection and notification of the failure, it isproblematic that the detection and notification of the failure does notlead to a suppression of the decrease of the cooling capacity of therefrigerating apparatus.

It is therefore the object of the present invention to suppress thedecrease of the cooling capacity of the refrigerating apparatus due to afailure of a fan motor.

=Configuration of Refrigerating Apparatus=

An exemplary configuration of a refrigerating apparatus 1A of a thirdembodiment will be described with reference to FIGS. 15 and 16. FIG. 15is a circuit diagram of an example of a first refrigerant circuit 10Aand a second refrigerant circuit 20A of the refrigerating apparatus 1Aof the third embodiment. FIG. 16 is a block diagram of an example of acontrol circuit responsible for controlling the first refrigerantcircuit 10A and the second refrigerant circuit 20A of the thirdembodiment.

As depicted in FIGS. 15 and 16, the refrigerating apparatus 1A includestwo substantially the same refrigerant circuits (the first refrigerantcircuit 10A and the second refrigerant circuit 20A), a first temperaturesensor 2Aa and a second temperature sensor 2Ab that detect an internaltemperature of a cold storage cabinet 2A, a first fan 14A and a firstfan motor 14Aa, a second fan 24A and a second fan motor 24Aa, a thermalfuse 141A (a third temperature sensor) of the first fan motor 14Aa, athermal fuse 241A (a fourth temperature sensor) of the second fan motor24Aa, a first current transformer 142A (a detecting device) that detectsthe current of the first fan motor 14Aa, a second current transformer242A (a detecting device) that detects the current of the second fanmotor 24Aa, and a microcomputer 31A (a control device). Therefrigerating apparatus 1A includes a temperature sensor 131A and atemperature sensor 231A that detect a temperature of an outlet portionof a condenser 13A and a temperature of an outlet portion of a condenser23A, respectively, and also includes a display (a notifying device) 41Aand a buzzer 42A (a notifying device) as a means for notifying a user,etc., of a failure of the fan motors 14Aa, 24Aa.

As depicted in FIG. 15, the first refrigerant circuit 10A includes afirst compressor 11A, a pre-condenser 12A and a condenser 13A (a firstcondenser), a pressure reducer 15A, and a first evaporator 16A and iscircularly configured with a predetermined pipe (a first refrigerantpipe) in such a manner that refrigerant discharged from the firstcompressor 11A returns to the same compressor 11A again.

The first compressor 11A compresses and discharges the suckedrefrigerant to the pre-condenser 12A.

The pre-condenser 12A is, for example, a pipe made of copper or aluminumthat is meandered and configured to radiate heat of the refrigerantdischarged from the first compressor 11A.

The condenser 13A is, for example, a pipe made of copper or aluminumthat is meandered and configured to further radiate heat of therefrigerant output from the pre-condenser 12A.

The first pressure reducer 15A is, for example, a capillary tube thatdepressurizes the refrigerant changed into the liquid phase due to heatradiation and condensation in the condenser 13A and outputs therefrigerant to the first evaporator 16A.

The first evaporator 16A is, for example, a pipe made of copper oraluminum configured to evaporate (vaporize) the refrigerantdepressurized by the first pressure reducer 15A and is affixed to theouter surface of the cold storage cabinet 2A of the refrigeratingapparatus 1A in a thermally contacting manner. That is to say, theinside of the cold storage cabinet 2A is cooled due to the coolingeffect at the time of evaporation of the refrigerant by the firstevaporator 16A. The refrigerant evaporated and changed into the gasphase is sucked into the first compressor 11A.

The same applies to the second refrigerant circuit 20A. The secondrefrigerant circuit 20A includes a second compressor 21A, apre-condenser 22A and a condenser 23A (a second condenser), a secondpressure reducer 25A, and a second evaporator 26A and is circularlyconnected with a predetermined pipe (a second refrigerant pipe) in sucha manner that the refrigerant discharged from the second compressor 21Areturns to the same compressor 21A again.

The condensers 13A, 23A are integrally provided on the same tube plate,for example, and are adjacently arranged in sequence on the tube platein the same air passage of the first fan 14A and the second fan 24A asdescribed later. The temperature sensor 131A and the temperature sensor231A described above are attached to the outlet portion of the condenser13A and the outlet portion of the condenser 23A, respectively, and thetemperature sensors 131A, 231A are electrically connected to the controlboard 30A as depicted in FIG. 16. Further, the first evaporator 16A andthe second evaporator 26A are disposed to concurrently refrigerate theinside of the cold storage cabinet 2A. That is to say, each of the firstevaporator 16A and the second evaporator 26A is made up of oneevaporation pipe (not depicted) and these two evaporation pipes are, forexample, attached to the outer surface of the cold storage cabinet 2A ina thermally contacting manner without overlapping each other.

The first temperature sensor 2Aa and the second temperature sensor 2Abare electrically connected to the control board 30A as depicted in FIG.16. Although the first temperature sensor 2Aa is a sensor configured tocontrol the first compressor 11A of the first refrigerant circuit 10Aand the second temperature sensor 2Ab is a sensor configured to controlthe second compressor 21A of the second refrigerant circuit 20A, both ofthe sensors 2Aa, 2Ab detect the internal temperature of the same coldstorage cabinet 2A. Both of the sensors 2Aa, 2Ab may be implemented bysharing a single sensor.

As depicted in FIG. 15, the first fan 14A and the second fan 24A are airblowers configured to blow air to the condenser 13A and the condenser23A, respectively, to facilitate the heat radiation of the refrigerant.As schematically depicted in FIG. 15, the condensers 13A, 23A areadjacently arranged in sequence in the same air passage formed by thefirst fan 14A and the second fan 24A located in parallel, and the fans14A, 24A are arranged in parallel so that air may be sent to both of thecondensers 13A, 23A. As schematically depicted in FIG. 15, the first fan14A and the second fan 24A are arranged to face the first compressor 11Aand the second compressor 21A, respectively. In the third embodiment,the direction of air blown by the first fan 14A and the second fan 24Ais a direction that is directed from the condensers 13A, 23A to thecompressors 11A, 21A (see an outline arrow of FIG. 15).

As depicted in FIG. 15, the first fan motor 14Aa and the second fanmotor 24Aa are power sources rotating the first fan 14A and the secondfan 24A, respectively. As depicted in FIG. 16, the first fan motor 14Aahas the thermal fuse 141A therein and the second fan motor 24Aa has thethermal fuse 241A therein. In the third embodiment, the thermal fuses141A, 241A are configured to be interrupted due to the increase intemperature of the first fan motor 14Aa and the second fan motor 24Aa inassociation with the increase in temperature of the condenses 13A, 23Awhen both the first fan 14A and the second fan 24A are stopped duringthe operation of the first refrigerant circuit 10A and the secondrefrigerant circuit 20A.

As depicted in FIG. 16, the first current transformer 142A and thesecond current transformer 242A are mounted on the control board 30A andare transformers that convert the current flowing through the first fanmotor 14Aa and the current flowing through the second fan motor 24Aainto respective voltages and output the voltages to the microcomputer31A. These current transformers 142A, 242Aa are serially connected tothe fan motors 14Aa, 24Aa, respectively. For example, in a case where alock current is flowing in the fan motors 14Aa, 24Aa, the voltage valuesof the corresponding current transformers 142A, 242A turn to valuescorresponding to the lock current and, for example, if no current isflowing due to disconnection of a circuit related to the fan motors14Aa, 24Aa, the voltage values of the corresponding current transformers142A, 242A turn to zero. That is to say, the operation states of the fanmotors 14Aa, 24Aa can be directly detected respectively by referring tothe voltage values of the current transformers 142A, 242A. This improvesthe accuracy of the failure detection of the fan motors 14Aa, 24Aa.

The microcomputer 31A is mounted on the control board 30A as depicted inFIG. 16 and includes a CPU 311A, a ROM 312A, a RAM 313A, etc., tocontrol the operation of the first compressor 11A and the secondcompressor 21A depending on the detection output of the firsttemperature sensor 2Aa and the second temperature sensor 2Ab, to controlthe operation of the first fan motor 14Aa and the second fan motor 24Aadepending on interruption/disinterruption by the thermal fuses 141A,241A, and to monitor the operation state of the first fan motor 14Aa andthe second fan motor 24Aa based on the detection output of the firstcurrent transfer 142A and the second current transfer 242A. The CPU 311Aexecutes processes related to the control and monitoring describedabove, the ROM 312A stores programs, etc., for the CPU 311A to executesuch processes, and the RAM 313A stores data necessary for suchprocesses.

For example, during the operation of the first refrigerant circuit 10A,the microcomputer 31A compares the internal temperature detected by thefirst temperature sensor 2Aa with a predetermined temperaturepreliminarily stored in the RAM 313A, stops the operation of the firstcompressor 11A through a predetermined relay (not depicted) if it isdetermined that the internal temperature is lower than or equal to thepredetermined temperature and starts the operation of the firstcompressor 11A through the predetermined relay if it is determined thatthe internal temperature is higher than the predetermined temperature.The same applies to the control of the operation of the secondcompressor 21A based on the detection output of the second temperaturesensor 2Ab. However, it is not limited thereto and, for example, if itis determined that the internal temperature is lower than or equal tothan the predetermined temperature, either one of the compressors 11A,21A may be stopped. As above, to keep the internal temperature of thecold storage cabinet 2A constant, the microcomputer 31A intermittentlyoperates the first compressor 11A and the second compressor 21A.

For example, in a case where the microcomputer 31A detects theinterruption of the thermal fuse 141A of the first fan motor 14Aa fromthe fact that the voltage value of the first current transformer 142A iszero, the microcomputer 31A stops applying the voltage to the first fanmotor 14Aa through a predetermined relay (not depicted). The sameapplies when stop applying the voltage to the second fan motor 24Aabased on the interruption of the thermal fuse 241A of the second fanmotor 24Aa.

As depicted in FIG. 16, the first compressor 11A, the second compressor21A, the first fan motor 14Aa, the second fan motor 24Aa, and aswitching power source 32A are supplied with electric power through athree-phase power cable 33A and a power switch 34A. The control board30A, etc., are supplied with electric power through the switching powersource 32A.

As above, since the first fan 14A and the second fan 24A are arranged toface the condenser 13A as depicted in FIG. 15, even if one of the fansstops blowing air, the condenser 13A is cooled by the air blown from theother fan. The same applies to the condenser 23A. As depicted in FIG.15, since the first fan 14A and the second fan 24A located in parallelare disposed to face the first compressor 11A and the second compressor21A, respectively, if one of the first fans 14A, 24A is rotating, thecompressor 11A, 21A not facing this fan at least partially receives airand is cooled. As depicted in FIG. 16, while the power supply to thefirst fan motor 14Aa and the second fan motor 24Aa is stopped by aninterruption of the respective internal thermal fuses 141A, 241Atherein, the power supply to the first compressor 11A and the secondcompressor 21A is stopped by the microcomputer 31A based on thedetection output of the first temperature sensor 2Aa and the secondtemperature sensor 2Ab. That is to say, the operation control for thefan motors 14Aa, 24Aa and the operation control of the compressors 11A,21A are independent of each other. Therefore, even if one of the fans14A, 24A stops during the operation of the refrigerating apparatus 1A,since the operation of the compressor 11A, 21A of the correspondingrefrigerant circuit 10A, 20A is not correspondingly stopped, the coolingcapacity of the refrigerating apparatus 1A is maintained at a levelexceeding the cooling capacity of only one of the refrigerant circuits10A, 20A.

==Operation of Refrigerating Apparatus==

Referring to FIG. 17, description will be made of an operation in whichthe refrigerating apparatus 1 having the above configuration detects afailure of the first fan motor 14Aa and the second fan motor 24Aa andmakes a notification thereof. FIG. 17 is a flowchart illustrating anexample of process procedures of the microcomputer 31A in the case ofdetection and notification of failure by the refrigerating apparatus 1Aof the third embodiment.

The microcomputer 31A obtains an absolute value of a difference valuebetween values A, B of the respective voltages outputted from the firstcurrent transformer 142A and the second current transformer 242A (S400).

The microcomputer 31A determines whether the absolute value of thedifference value obtained at step S400 is greater than or equal to apredetermined value X preliminarily stored in the RAM 313A (S401). Thispredetermined value X is a value determined in advance based on avoltage difference between the first current transformer 142A and thesecond current transformer 242A that may occur in a case where one ofthe first current transformer 142A and the second current transformer242A is stopped and the other one is rotating. The predetermined value Xof the present embodiment is, for example, a smaller one of thefollowing two values. That is, a first value is a value obtained bysubtracting, from a voltage value corresponding to the lock currentflowing through the stopped one of the two fan motors 14Aa, 24Aa, avoltage value corresponding to the current flowing through the otherrotating one of the two fan motors 14Aa, 24Aa that is rotating. A secondvalue is a voltage value corresponding to the current flowing throughthe rotating one of the two fan motors 14Aa, 24Aa. Since no currentflows through the other stopped one of the two fan motors 14Aa, 24Aa,the corresponding voltage value is zero.

If it is determined that the absolute value of the difference valueobtained at step S400 is less than the predetermined value X (S401: NO),the microcomputer 31A executes the process of step S400 again. That isto say, the microcomputer 31A determines that the operation state of thetwo fan motors 14Aa, 24Aa is a state in which both of the fan motors arerotating and continues to monitor the operation state of the two fanmotors 14Aa, 24Aa.

If it is determined that the absolute value of the difference valueobtained at step S400 is greater than or equal to the predeterminedvalue X (S401: YES), the microcomputer 31A stores the values A, B of thevoltages respectively outputted from the first current transformer 142Aand the second current transformer 242A into the RAM 313A in such amanner that they correspond to information indicating the correspondingfan motors 14Aa, 24Aa (S402). That is to say, the microcomputer 31Adetermines that the operation state of the two fan motors 14Aa, 24Aa isa state in which one of the fan motors is stopped and the other isrotating and determines which of the fan motor 14Aa or 24Aa has failedbased on the individual voltage values A, B of the current transformers142A, 242A as described later.

The microcomputer 31A determines whether the voltage value A of thefirst current transformer 142A corresponding to the first fan motor 14Aais greater than or equal to a predetermined value Y preliminarily storedin the RAM 313A (S403). The predetermined value Y is a voltage valuecorresponding to the lock current in a case where the first fan motor14Aa is stopped and the lock current is applied to the first currenttransformer 142A. If it is determined that the voltage value A of thefirst current transformer 142A is greater than or equal to thepredetermined value Y (S403: YES), the microcomputer 31A displays on thedisplay 41A that the first fan motor 14Aa (the motor corresponding to A)has failed and set off the buzzer 42A, for example, for a predeterminedtime measured by a predetermined timer (not depicted) (S404), andexecutes the process of step S405 described later. That is to say, inthis case, it is determined that at least the first fan 14A is stoppeddue to the lock of the first fan motor 14Aa and a user, etc., arenotified of this determination result.

If it is determined that the voltage value A of the first currenttransformer 142A is less than the predetermined value Y (S403: NO), themicrocomputer 31A determines whether the voltage value B of the secondcurrent transformer 242A corresponding to the second fan motor 24Aa isgreater than or equal to a predetermined value Y preliminarily stored inthe RAM 313A (S408). The predetermined value Y is a voltage valuecorresponding to the lock current in a case where the second fan motor24Aa is stopped and the lock current is flowing through the secondcurrent transformer 242A. If it is determined that the voltage value Bof the second current transformer 242A is greater than or equal to thepredetermined value Y (S408: YES), the microcomputer 31A displays on thedisplay 41A that the second fan motor 24Aa (the motor corresponding toB) has failed and sets off the buzzer 42A, for example, for apredetermined time (S409), and executes the process of step S405described later. That is to say, in this case, it is determined that atleast the second fan 24A is stopped due to the lock of the second fanmotor 24Aa and a user, etc., are notified of this determination result.

If it is determined that the voltage value B of the second currenttransformer 242A is less than the predetermined value Y (S408: NO), themicrocomputer 31A determines whether the voltage value A of the firstcurrent transformer 142A corresponding to the first fan motor 14Aa iszero (S410). If it is determined that the voltage value A of the firstcurrent transformer 142A is zero (S410: YES), the microcomputer 31Adisplays on the display 41A that the first fan motor 14Aa (the motorcorresponding to A) has failed and sets off the buzzer 42A, for example,for a predetermined time (S411), and executes the process of step S405described later. In this case, it is determined that at least the firstfan 14A is stopped, for example, due to disconnection, etc., of acircuit related to the first fan motor 14Aa and a user, etc., arenotified of this determination result.

If it is determined that the voltage value A of the first currenttransformer 142A is not zero (i.e., greater than zero) (S410: YES), themicrocomputer 31A determines whether the voltage value B of the secondcurrent transformer 242A corresponding to the second fan motor 24Aa iszero (S412). If it is determined that the voltage value B of the secondcurrent transformer 242A is zero (S412: YES), the microcomputer 31Adisplays on the display 41A that the second fan motor 24Aa (the motorcorresponding to B) has failed and sets off the buzzer 42A, for example,for a predetermined time (S413), and executes the process of step S405described later. In this case, it is determined that at least the secondfan 24A is stopped, for example, due to disconnection, etc., of acircuit related to the second fan motor 24Aa and a user, etc., arenotified of this determination result.

If it is determined that the voltage value B of the second currenttransformer 242A is not zero (i.e., greater than zero) (S412: NO), themicrocomputer 31A executes the process of step S402 again. Themicrocomputer 31A newly samples the respective voltage values A, B ofthe first current transformer 142A and the second current transformer242A and, based on the new voltage values A, B, determines again whichof the fan motor 14Aa or 24Aa has failed.

As above, since the notification is made at the time one of the two fanmotors 14Aa, 24Aa has failed, the notified user, etc., can identify thefailed one and repair/replace this fan motor while the other fan motoris in operation to maintain the heat exchange amount of the bothcondensers 13A, 23A. This leads to suppression in the reduction of thecooling capacity of the refrigerating apparatus 1A. Setting off thebuzzer 42A for a predetermined time prompts the user, etc., to see thedisplay on the display 41A and this further ensures the notification ofthe failure. At steps S400 and S401, since a determination is first madeon whether at least one of the fan motors 14A, 24A has failed based onlyon the difference value of the voltage values A, B of the two currenttransformers 142A, 242A, the microcomputer 31A requires a smallerprocess load. That is to say, the processing capacity of the CPU 311A,the capacity of the RAM 313A, etc., can be suppressed to reduce themanufacturing cost of the refrigerating apparatus 1A.

In the third embodiment, in a case where a notification is made that oneof the two fan motors 14Aa, 24Aa has failed (S404, S409, S411, or S413),the microcomputer 31A refers to the temperature of the outlet portion ofthe condenser 13A and the temperature of the outlet portion of thecondenser 23A respectively detected by the temperature sensor 131A andthe temperature sensor 231A (S405) and executes the following processbased on these temperatures.

The microcomputer 31A determines whether the two temperatures detectedat step S405 are greater than or equal to a predetermined value Zpreliminarily stored in the RAM 313A (S406). The predetermined value Zis a value corresponding to the temperatures in a case where thetemperatures has increased in the outlet portions of the condensers 13A,23A due to a failure in both of the first fan motor 14Aa and the secondfan motor 24Aa.

For example, if it is determined that one of the two temperatures isless than the predetermined value Z (S406: NO), the microcomputer 31Aexecutes the process of step S400 again.

For example, if it is determined that the two temperatures are greaterthan or equal to the predetermined value Z (S406: YES), themicrocomputer 31A changes a display on the display 41A at above stepsS404, S409, S411, or S413 to a display that there is a failure in thefirst fan motor 14Aa and the second fan motor 24Aa (the motorscorresponding to A, B), sets off the buzzer 42A, for example, for apredetermined time (S407), and terminates the process. In this case, itis determined that both of the first fan 14A and the second fan 24A arestopped, for example, due to the lock of one of the two fan motors 14Aa,24Aa and the disconnection of the other, and that, as a result, thetemperatures of the outlet portions of the condensers 13A, 23A aregreater than or equal to the predetermined temperature, and a user,etc., are notified of this determination result.

In the third embodiment, for example, in a case where the temperatureshave increased in the condensers 13A, 23A due to the locking of the twofan motors 14Aa, 24Aa, since the temperatures of the two fan motors14Aa, 24Aa also correspondingly increase, the thermal fuses 141A, 241Aare interrupted. Therefore, the lock current that was flowing in the fanmotors 14Aa, 24Aa turns to zero. Such operation control of the fanmotors 14Aa, 24Aa enables the avoidance of wasteful power consumptiondue to the lock current.

However, neither the state in which the lock current is flowing throughthe two fan motors 14Aa, 24Aa nor the state in which the current is notflowing through the two fan motors 14Aa, 24Aa due to the interruption ofthe thermal fuses 141A, 241A can be determined with the process of abovestep S401. That is to say, the difference value of the voltage values A,B of the two current transformers 142A, 242A is substantially zero ineither case.

Therefore, although not depicted, the microcomputer 31A is configured toexecute a process similar to the above steps S405 to S407, for example,at each of the predetermined time intervals measured by a predeterminedtimer (not depicted) separately from the process of the above step S401and the subsequent processes. That is to say, the microcomputer 31Aregularly determines the presence of failure of the both fan motors14Aa, 24Aa from the detection of temperatures of the outlet portions ofthe condensers 13A, 23A and if it is determined that there is a failurein both of them, a user, etc., are notified of the failure.Alternatively, the microcomputer 31A may regularly determine thepresence of failure of the both fan motors 14Aa, 24Aa from the detectionof voltages of the two current transformers 142A, 242A. That is to say,if the both voltage values A, B are zero, it is determined that there isa failure in the both fan motors 14Aa, 24Aa.

Other Embodiments

The above embodiments of the present invention are simply forfacilitating the understanding of the present invention and are not inany way to be construed as limiting the present invention. The presentinvention may variously be changed or altered without departing from itsspirit and encompass equivalents thereof.

Although only the condensers 14A, 23A are integrally provided on thesame tube plate and are adjacently arranged in sequence on the tubeplate in the same air passage of the first fan 14A and the second fan24A in the above embodiment, it is not limited thereto. For example, thepre-condensers 12A, 22A may also integrally be provided on the same tubeplate as the condensers 13A, 23A and may adjacently be arranged insequence on the tube plate in the same air passage of the first fan 14Aand the second fan 24A.

In the above embodiment, although the notifying devices are the display41A and the buzzer 42A, it is not a limited thereto and may be basicallyany means for notifying a user, etc., of the failure of the fan motors14Aa, 24Aa. Although the notification only indicates which of the fanmotors 14Aa, 24Aa has failed, it is not limited thereto and, forexample, details of the failure based on the voltage values A, B of thecurrent transformers 142A, 242A may be added (such as the lock or thedisconnection of the circuit).

In the above embodiment, although the processes of steps S405 to S407 bythe microcomputer 31A are executed after the respective processes ofsteps S404, S409, S411, and S413, it is not limited thereto.

Hereinafter, as depicted in FIG. 18, the microcomputer 31A may, afterhaving determined that one of the fan motors has failed, themicrocomputer 31A may determine the presence of a failure of the otherfan motor and then make a notification of the final determination result(one has failed or both have failed) only once.

FIG. 18 is a flowchart of another example of process procedures of themicrocomputer 31A in the case of detection and notification of failureby the refrigerating apparatus 1A of the third embodiment. The processesof steps S500 to S502 of FIG. 18 are the same as the respectiveprocesses of steps S400 to S402 of FIG. 17. The determination processesof steps S503, S508, S513, and S518 of FIG. 18 are the same as therespective determination processes of steps S403, S408, S410, and S412of FIG. 17. That is to say, with these processes, it is determined whichof the two fan motors 14Aa, 24Aa has a failure and whether the failureis the lock or the disconnection of the circuit.

If it is determined that the voltage value A of the first currenttransformer 142A is greater than or equal to the above predeterminedvalue Y (S503: YES), the microcomputer 31A refers to the temperatures ofthe outlet portions of the condensers 13A, 23A respectively detected bythe temperature sensors 131A, 231A (S504) and determines whether the twotemperatures are greater than or equal to the above predetermined valueZ (S505). For example, if it is determined that one of the twotemperatures is less than the predetermined value Z (S505: NO), themicrocomputer 31A displays on the display 41A that the first fan motor14Aa (the motor corresponding to A) has failed and sets off the buzzer42A, for example, for a predetermined time (S507), and executes theprocess of step S500 again. On the other hand, for example, if it isdetermined that the two temperatures are greater than or equal to thepredetermined value Z (S505: YES), the microcomputer 31A displays on thedisplay 41A that there is a failure in both of the fan motors 14Aa, 24Aa(the motors corresponding to A, B), sets off the buzzer 42A, forexample, for a predetermined time (S506), and terminates the process.

If it is determined that the voltage value B of the second currenttransformer 242A is greater than or equal to the above predeterminedvalue Y (S508: YES), the microcomputer 31A refers to the temperatures ofthe outlet portions of the condensers 13A, 23A in a manner similar tothe above (S509) and determines whether the two temperatures are greaterthan or equal to the above predetermined value Z (S510). If it isdetermined that one of the two temperatures is less than thepredetermined value Z (S510: NO), the microcomputer 31A makes anotification in a manner similar to the above to indicate that thesecond fan motor 24Aa (the motor corresponding to B) has failed (S512),and executes the process of step S500 again. On the other hand, if it isdetermined that the two temperatures are greater than or equal to thepredetermined value Z (S510: YES), the microcomputer 31A makes anotification in a manner similar to the above to indicate that there isa failure in both of the fan motors 14Aa, 24Aa (the motors correspondingto A, B) (S511) and terminates the process.

If it is determined that the voltage value A of the first currenttransformer 142A is zero (S513: YES), the microcomputer 31A refers tothe temperatures of the outlet portions of the condensers 13A, 23A in amanner similar to the above (S514) and determines whether the twotemperatures are greater than or equal to the above predetermined valueZ (S515). If it is determined that one of the two temperatures is lessthan the predetermined value Z (S515: NO), the microcomputer 31A makes anotification in a manner similar to the above to indicate that the firstfan motor 14Aa (the motor corresponding to A) has failed (S517), andexecutes the process of step S500 again. On the other hand, if it isdetermined that the two temperatures are greater than or equal to thepredetermined value Z (S515: YES), the microcomputer 31A makes anotification in a manner similar to the above to indicate that there isa failure in both of the fan motors 14Aa, 24Aa (the motors correspondingto A, B) (S516) and terminates the process.

If it is determined that the voltage value B of the second currenttransformer 242A is zero (S518: YES), the microcomputer 31A refers tothe temperatures of the outlet portions of the condensers 13A, 23A in amanner similar to the above (S519) and determines whether the twotemperatures are greater than or equal to the above predetermined valueZ (S520). If it is determined that one of the two temperatures is lessthan the predetermined value Z (S520: NO), the microcomputer 31A makes anotification in a manner similar to the above to indicate that thesecond fan motor 24Aa (the motor corresponding to B) has failed (S522),and executes the process of step S500 again. On the other hand, if it isdetermined that the two temperatures are greater than or equal to thepredetermined value Z (S520: YES), the microcomputer 31A makes anotification in a manner similar to the above to indicate that there isa failure in both of the fan motors 14Aa, 24Aa (the motors correspondingto A, B) (S521), and terminates the process.

With the above process, in a case where the failure of both of the fanmotors 14Aa, 24Aa is displayed, an instruction for displaying thefailure of the one fan motor on the display 41 can be skipped at theprevious step and, therefore, the program can correspondingly besimplified.

The refrigerating apparatus of the third embodiment is applicable to therefrigerating apparatus of the first embodiment.

What is claimed is:
 1. A refrigerating apparatus comprising: a firstrefrigerant circuit including a first compressor, a first condenser, afirst pressure reducer, and a first evaporator, connected circularlywith a first refrigerant pipe, a refrigerant discharged from the firstcompressor being condensed at the first condenser and thereafterevaporated at the first evaporator to acquire a cooling effect; a secondrefrigerant circuit including a second compressor, a second condenser, asecond pressure reducer, and a second evaporator, connected circularlywith a second refrigerant pipe, a refrigerant discharged from the secondcompressor being condensed at the second condenser and thereafterevaporated at the second evaporator to acquire a cooling effect; atemperature sensor configured to detect a temperature of an internalportion of a cold storage cabinet, the first evaporator and the secondevaporator being disposed to cool the internal portion at the same time;and a first control device configured to perform control so that atleast one of the first compressor and the second compressor must beoperated, wherein the first control device is further configured tocontrol the first compressor and the second compressor in such a mannerthat both the first compressor and the second compressor are operatedeach time a temperature detected by the temperature sensor reaches afirst temperature, and only one of the first compressor and the secondcompressor is operated as well as the first compressor and the secondcompressor are alternately operated, each time a temperature detected bythe temperature sensor reaches a second temperature lower than the firsttemperature.
 2. The refrigerating apparatus according to claim 1,further comprising: a second control device configured to control thefirst compressor and the second compressor in such a manner that thefirst compressor and the second compressor start being alternatelyoperated each time a temperature detected by the temperature sensorreaches the first temperature, and are continuously operated until thedetected temperature reaches the second temperature; and a firstswitching device configured to switch over a control by the secondcontrol device to a control by the first control device when atemperature detected by the temperature sensor reaches a thirdtemperature higher than the first temperature, and switch over a controlby the first control device to a control by the second control devicewhen a temperature detected by the temperature sensor reaches a fourthtemperature lower than the second temperature.
 3. The refrigeratingapparatus according to claim 2, comprising: a timer configured tomeasure a time during which a temperature detected by the temperaturesensor is a temperature between the first temperature and the secondtemperature, when the first compressor and the second compressor startbeing alternately operated; and a second switching apparatus configuredto switch between an operation of the first compressor and an operationof the second compressor, when the measured time of the timer hasexceeded a predetermined time.
 4. The refrigerating apparatus accordingto claim 1, wherein: the first evaporator and the second evaporator aredisposed so as to cool a same internal portion at the same time, thetemperature sensor includes a first temperature sensor and a secondtemperature sensor for controlling respective operations of the firstcompressor and the second compressor to enable detection of atemperature of the same internal portion, a first fan and a second fanare disposed in parallel so as to blow air to the first condenser andthe second condenser adjacently disposed in sequence in a same airpassage, the refrigerating apparatus further comprises a second controldevice configured to control the first fan and the second fan based onrespective temperatures detected by the first sensor and the secondsensor, the first fan and the second fan are disposed to face the firstcondenser, and in an air passage, the first fan and the second fan facethe first compressor and the second compressor, respectively.
 5. Therefrigerating apparatus according to claim 1, comprising: a firsttemperature sensor and a second temperature sensor configured to serveas the temperature sensor configured to detect the temperature of theinternal portion of the cold storage cabinet; a first fan; a second fan;a first fan motor configured to rotate the first fan; a second fan motorconfigured to rotate the second fan; a third temperature sensorconfigured to detect a temperature of the first fan motor; a fourthtemperature sensor configured to detect a temperature of the second fanmotor; a detecting device configured to detect a current of the firstfan motor and a current of the second fan motor; and a second controldevice, wherein: the first evaporator and the second evaporator aredisposed to cool the internal portion at the same time, the first fanand the second fan are disposed in parallel so as to blow air to thefirst condenser and the second condenser adjacently disposed in sequencein a same air passage of the first fan and the second fan, and thesecond control device is configured to control respective operations ofthe first compressor and the second compressor depending on detectionoutputs of the first temperature sensor and the second temperaturesensor, control respective operations of the first fan motor and thesecond fan motor depending on detection outputs of the third temperaturesensor and the fourth temperature sensor, and monitor operation statesof the first fan motor and the second fan motor based on the detectionoutput of the detecting device to make a notification of failure of thefirst fan motor and the second fan motor.
 6. The refrigerating apparatusaccording to claim 5, wherein: the detecting apparatus includes a firstcurrent transformer and a second current transformer configured todetect a current of the first fan motor and a current of the second fanmotor, respectively, as voltages, and the second control device isconfigured to monitor the operation states of the first fan motor andthe second fan motor based on the voltages of the first currenttransformer and the second current transformer.
 7. The refrigeratingapparatus according to claim 6, wherein the second control devicedetermines whether the first fan motor and the second fan motor hasfailed based on a difference value between a voltage of the firstcurrent transformer and a voltage of the second current transformer. 8.The refrigerating apparatus according to claim 7, wherein in a casewhere an absolute value of the difference value is greater than apredetermined value, the second control device determines that either orboth of the first fan motor and the second fan motor has or have failed.9. A refrigerating apparatus comprising: a first refrigerant circuitincluding a first compressor, a first condenser, a first pressurereducer, and a first evaporator, connected circularly with a firstrefrigerant pipe, a refrigerant discharged from the first compressorbeing condensed at the first condenser and thereafter evaporated at thefirst evaporator to acquire a cooling effect; a second refrigerantcircuit including a second compressor, a second condenser, a secondpressure reducer, and a second evaporator, connected circularly with asecond refrigerant pipe, a refrigerant discharged from the secondcompressor being condensed at the second condenser and thereafterevaporated at the second evaporator to acquire a cooling effect; atemperature sensor configured to detect a temperature of an internalportion of a cold storage cabinet, the first evaporator and the secondevaporator being disposed to cool the internal portion at the same time;a first control device configured to control the first compressor andthe second compressor in such a manner that both the first compressorand the second compressor are operated each time a temperature detectedby the temperature sensor reaches a first temperature, and the firstcompressor and the second compressor are alternately operated each timea temperature detected by the temperature sensor reaches a secondtemperature lower than the first temperature; a second control deviceconfigured to control the first compressor and the second compressor insuch a manner that the first compressor and the second compressor startbeing alternately operated each time a temperature detected by thetemperature sensor reaches the first temperature, and are continuouslyoperated until the detected temperature reaches the second temperature;and a first switching device configured to switch over a control by thesecond control device to a control by the first control device when atemperature detected by the temperature sensor reaches a thirdtemperature higher than the first temperature, and switch over a controlby the first control device to a control by the second control devicewhen a temperature detected by the temperature sensor reaches a fourthtemperature lower than the second temperature.
 10. The refrigeratingapparatus according to claim 9, further comprising: a timer configuredto measure a time during which a temperature detected by the temperaturesensor is a temperature between the first temperature and the secondtemperature, when the first compressor and the second compressor startbeing alternately operated; and a second switching apparatus configuredto switch between an operation of the first compressor and an operationof the second compressor, when the measured time of the timer hasexceeded a predetermined time.
 11. A refrigerating apparatus comprising:a first refrigerant circuit including a first compressor, a firstcondenser, a first pressure reducer, and a first evaporator, connectedcircularly with a first refrigerant pipe, a refrigerant discharged fromthe first compressor being condensed at the first condenser andthereafter evaporated at the first evaporator to acquire a coolingeffect; a second refrigerant circuit including a second compressor, asecond condenser, a second pressure reducer, and a second evaporator,connected circularly with a second refrigerant pipe, a refrigerantdischarged from the second compressor being condensed at the secondcondenser and thereafter evaporated at the second evaporator to acquirea cooling effect; a temperature sensor configured to detect atemperature of an internal portion of a cold storage cabinet, the firstevaporator and the second evaporator being disposed to cool the internalportion at the same time; and a first control device configured tocontrol the first compressor and the second compressor in such a mannerthat both the first compressor and the second compressor are operatedeach time a temperature detected by the temperature sensor reaches afirst temperature, and the first compressor and the second compressorare alternately operated each time a temperature detected by thetemperature sensor reaches a second temperature lower than the firsttemperature, wherein: the first evaporator and the second evaporator aredisposed so as to cool a same internal portion at the same time, thetemperature sensor includes a first temperature sensor and a secondtemperature sensor for controlling respective operations of the firstcompressor and the second compressor to enable detection of atemperature of the same internal portion, a first fan and a second fanare disposed in parallel so as to blow air to the first condenser andthe second condenser adjacently disposed in sequence in a same airpassage, the refrigerating apparatus further comprises a second controldevice configured to control the first fan and the second fan based onrespective temperatures detected by the first sensor and the secondsensor, the first fan and the second fan are disposed to face the firstcondenser, in an air passage, the first fan and the second fan face thefirst compressor and the second compressor, respectively.
 12. Arefrigerating apparatus comprising: a first refrigerant circuitincluding a first compressor, a first condenser, a first pressurereducer, and a first evaporator, connected circularly with a firstrefrigerant pipe, a refrigerant discharged from the first compressorbeing condensed at the first condenser and thereafter evaporated at thefirst evaporator to acquire a cooling effect; a second refrigerantcircuit including a second compressor, a second condenser, a secondpressure reducer, and a second evaporator, connected circularly with asecond refrigerant pipe, a refrigerant discharged from the secondcompressor being condensed at the second condenser and thereafterevaporated at the second evaporator to acquire a cooling effect; atemperature sensor configured to detect a temperature of an internalportion of a cold storage cabinet, the first evaporator and the secondevaporator being disposed to cool the internal portion at the same time;a first control device configured to control the first compressor andthe second compressor in such a manner that both the first compressorand the second compressor are operated each time a temperature detectedby the temperature sensor reaches a first temperature, and the firstcompressor and the second compressor are alternately operated each timea temperature detected by the temperature sensor reaches a secondtemperature lower than the first temperature; a first temperature sensorand a second temperature sensor configured to serve as the temperaturesensor configured to detect the temperature of the internal portion ofthe cold storage cabinet; a first fan; a second fan; a first fan motorconfigured to rotate the first fan; a second fan motor configured torotate the second fan; a third temperature sensor configured to detect atemperature of the first fan motor; a fourth temperature sensorconfigured to detect a temperature of the second fan motor; a detectingdevice configured to detect a current of the first fan motor and acurrent of the second fan motor; and a second control device, wherein:the first evaporator and the second evaporator are disposed to cool theinternal portion at the same time, the first fan and the second fan aredisposed in parallel so as to blow air to the first condenser and thesecond condenser adjacently disposed in sequence in a same air passageof the first fan and the second fan, and the second control device isconfigured to control respective operations of the first compressor andthe second compressor depending on detection outputs of the firsttemperature sensor and the second temperature sensor, control respectiveoperations of the first fan motor and the second fan motor depending ondetection outputs of the third temperature sensor and the fourthtemperature sensor, and monitor operation states of the first fan motorand the second fan motor based on the detection output of the detectingdevice to make a notification of failure of the first fan motor and thesecond fan motor.
 13. The refrigerating apparatus according to claim 12,wherein: the detecting apparatus includes a first current transformerand a second current transformer configured to detect a current of thefirst fan motor and a current of the second fan motor, respectively, asvoltages, and the second control device is configured to monitor theoperation states of the first fan motor and the second fan motor basedon the voltages of the first current transformer and the second currenttransformer.
 14. The refrigerating apparatus according to claim 13,wherein the second control device determines whether the first fan motorand the second fan motor has failed based on a difference value betweena voltage of the first current transformer and a voltage of the secondcurrent transformer.
 15. The refrigerating apparatus according to claim14, wherein in a case where an absolute value of the difference value isgreater than a predetermined value, the second control device determinesthat either or both of the first fan motor and the second fan motor hasor have failed.